Texas Edwards Plateau

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The Edwards Plateau, called affectionately the Texas Hill Country, is one of Texas’ major Vegetational or Land Resource Areas. Unlike some of the Vegetational Areas (Blackland Prairie, Cross Timbers and Associated  Prairies, Post Oak Savanna, Pineywoods, and Coastal Prairies and Marshes) which are biotic or floristic units or designations, the Edwards Plateau (along with the Trans Pecos Basin and Range and High Plains Vegetational Areas) is a geologic unit, a delineation based on physiographic province, and not a biological unit. Therefore, there is less botanical unity in the Edwards Plateau range types and sites. Included within the Edwards Plateau Region is the granitic Central Basin, the Stockton Plateau, and the Balcones Escarpment. The exact physiographic units to include as part of the Edwards Plateau remains uncertain with various authors using different criteria and, thus, including different locations (Riskind and Diamond in Amos and Gehlbach, 1988, ps. 1-5). For example, some authors included the Stockton Plateau as part of the greater Edwards Plateau while other authors interpreted the Stockton Plateau as part of the Trans-Pecos Basin and Range province (hence the Vegetational or Land Resource of that name). Strictly speaking the Stockton Plateau is part of the Great Plains physiographic province (details below) and not part of the Basin and Range Province (Fenneman, 1931, p. 50). Based on that geologic ("bedrock") basis the current author herein treated the Stockton Plateau as part of the Edwards Plateau. This treatment was inconsistent with some workers cited in Amos and Gehlbach (1988, p. 2), but there was inconsistency even within Amos and Gehlbach (1988, ps. 2, 25). Inclusion of the Stockton Plateau as part of the Edwards Plateau was consistent with the traditional designations of Texas Vegetational Areas (Gould, 1962, ps. 1, 11; Correll and Johnston, 1979, map 1, ps. 9-10, 12). Western (semiarid) and southern boundaries of the Edwards Plateau (with eastern border of Trans-Pecos Basin and Range Region and plains of Rio Grande) as a natural spatial unit describing range vegetation is even more confused and complicated. There is not complete agreement (ie. matching overlap) between the physiographically defined Edwards Plateau vegetational area with the corresponding potential natural vegetation (Kuchler, 1964, map in Garrison et al., 1977) and level III ecoregions (Griffith et al., 2004). As cited in the preceding paragraph, Texas range scientists, primarily taxonomists and plant ecologists (Gould, 1962, ps. 1, 11; Correll and Johnston, 1979, map 1, ps. 9-10, 12), traditionally mapped the Edwards Plateau as a vegetational or land resource area that extends far west of the Pecos River (almost to the Big Bend of the Rio Grande) and as far south as the Rio Grande. By contrast, Kuchler (1964; map in Garrison et al., 1977) extended the Chihuhuan Desert of the general Trans-Pecos Basin and Range south of the Edwards Plateau savannahs (to the Rio Grande) and eastward to contact the northwestern tip of the Rio Grande Plains while adding a ceniza (Leucophyllum frutescens)-dominated scrub savanna farther east and along ridges and floodplain of the Rio Grande. Griffith et al. (2004) mapped the Chihuhuan Desert, Edwards Plateau, and Rio Grande (Southern Texas) Plains ecoregions (level III) in similar mapping fashion to, though not in complete agreement with, units of natural vegetation (Kuchler,1964; map in Garrison et al., 1977). Griffith et al. (2004) extended the Chihuhuan Desert contacts along the Rio Grande clear to the Rio Grande Plains with an Edwards Bajada level IV ecoregion of the Rio Grande (Southern Texas) Plains and not of the Edwards Plateau ecoregion. Neither the potential natural vegetation (maps of Kuchler, 1964; in Garrison et al., 1977) nor the ecoregion of Edwards Plateau (Griffith et al., 2004) extend to the Rio Grande or to the Pecos River. A similar situation of confusion exist with regard to placement of the Lampasas Cut Plain into a vegetational or land resource area. Historically the Lampasas Cut Plain was interpreted as part of either of the Edwards Plateau or of the Cross Timbers and Prairies vegetational area. Traditionally prominent Texas authorities (Gould, 1962, ps. 1, 10, 11-12; Correll and Johnston, 1979, Map 1, ps. 7, 9-10; Griffith et al., 2004) regarded the Lampasas Plain as part of the Cross Timbers-Grand Prairie, but notable exceptions, including authors in Amos and Gehlbach (1988, ps. 1-5, 12, 15, 57, 76, 116, 118) and Texas Parks & Wildlife (various undated vegetation maps), placed the Lampasas Plain in the Edwards Plateau. Based on physiography (= physiographic provinces)-- the second most distinguishing criterion after climate in designating major units of vegetation-- placement within the Edwards Plateau is most precise. Fenneman (1931, p. 55-56) distinguished the Lampasas Cut Plain from the Edwards Plateau, but he (Fenneman, 1931, ps. 55-56; Fenneman, 1938, ps. 100-101, 106) included both the Edwards Plateau and the Lampasas Cut Plain as parts of the Great Plains physiographic province while the Eastern and Western Cross Timbers and Grand Prairie were included in the Coastal Plains physiographic province (Fenneman, 1938, ps. 100-106). Fenneman specified that even though the Lampasas Cut Plain "is genetically a part of the Coastal Plain" (Fenneman, 1938, ps. 100-101) this physiographic unit was "assigned to the Great Plains province" (Fenneman, 1938, p. 106). Clearly the Lampasas Cut Plain is aligned more closely physiographically with the Edwards Plateau than with the Cross Timbers and Grand Prairie. This affinity becomes even stronger when reference is made to the more general or greater Edwards Plateau. It might be helpful as regards designation and inclusion of physiographic provinces, vegetational areas, ecoregions, range types, etc. to explain that a further confounding factor is that of counties (in this case, Texas counties). In rural areas, the county is the fundamental unit of government. This is especially true in regard to activities by the Texas Agricultural (Cooperative) Extension Service (ie. county agent offices) and related functions of the land grant university as well as various activities by United States Departmsnes of Agricultural and Interior. Soil surveys, including range site descriptions, by the (Soil) Natural Resorces Conservation Service and various cooperting organizations are usually compiled by or as to county. Delineation of a natural unit like the Edwards Plateau is often on basis on a political uint, the county. Thus, some important aspects of the Edwards Plateau were studied, explained, or mapped roughly by county lines in Amos and Gehlbach (1988, Fig 1, ps. 26, 32, 33, 35, 36, 39). Each of the different general units or divisions of the Edwards Plateau has a distinct overall (and component) vegetation. There are transitions in vegetation where the Edwards Plateau joins the other Vegetational Areas like the Cross Timbers, Rolling Red Plains, and Trans-Pecos Basin-Range, the latter Area designated by proper title of the Basin and Range physiographic province. This subdivisions (Amos and Gehlbach (1988. ps. 1-6) were indicated in the treatment below. It was explained previously that the Edwards Plateau is part of the Great Plains physiographic province which in Texas also includes the High Plains (= Staked Plains or Llano Estacado) and Rolling Red Plains. The Balcones Escarpment that formed along the Balcones Fault Zone is the extreme edge of the Edwards Plateau and this scarp forms the southern and eastern boundaries of the Great Plains province where this physiographic unit joins the Gulf Coastal Plain physiographic province (Fenneman, 1931, ps. 51, 53-55; Fenneman, 1938, ps. 100, 102; Hunt, 1974, ps. 210, 224, 228, 243, 326, 341; Trimble, 1990, ps. 46-48). Geographic location, especially in relation to other physiographic provinces, as well as geologic/edaphic features combined with a similar "hodge-podge" of climatic variables are causative agents in formation of the unique vegetation of the diverse Edwards Plateau. There were early accounts of Texas vegetation including some reference to the Edwards Plateau. The reader is referred to the translated or edited journals of Olmsted (1857; later editions available such as that of Rybczynski, 2004), Roemer (Mueller, 1935), Lindheimer (Gohne, 1991), Riddell (Breeden, 1994). Irrespective of these excellent descriptions, the overall vegetation— if there was one or, even, several general forms — was far from clear largely because Edwards Plateau did “not appear in any pre-1860 description of Texas” (Weniger in Amos and Gehlbach, 1988, p. 19). Weniger (p. 21) noted: “There is not one early report of completely open country on the Edwards Plateau”.  He concluded:

“The historic Plateau was thus a blend zone with woody vegetation predominating  northward in proximity to the wooded Crosss Timbers and grasslands predominating near the eastern Blackland, southern Coastal, and western short-grass prairie regions” (Weniger in Amos and Gehlbach, 1988, ps. 22-23).

The definitive work on Edwards Plateau range is Edwards Plateau Vegetation- Plant Ecological Studeis in Central Texas (Amos and Behlbach, 1988). Highly recommended. Arrangement of range vegetational units in coverage below followed this reference as modified by Correll and Johnston (1979) which followed traditional demarcations.

Historical and Tecnhical Note: Texas' Edwards Plateau is but one of ten or eleven (depending on authority doing the counting) natural subdivisions of the state that over a number of years have been designated variously as "vegetational areas", "land resource areas", and, more recently, "natural regions and subregions". Obviously in geographical scale and cartography usage the former or older designtions are more accurate and correct conventions than the "up-to-date" distinctions (typical, hugh?) given that spatial scale of mapping units is less than that traditionally used for regional size. Mapping of Texas natural areas has been a long-standing endeavor that likely traces back to travels and journals of the first explorers and scientists. Modern attempts are usually accorded to the Catalogue of the Flora of Texas (Cory and Parks, 1937) and The Vegetation of Texas (Tharp, 1939) followed by Texas Plants-- A Checklist and Ecological Summary edited by Gould (1962) and Manual of the Vascular Plants of Texas by Correll and Johnston (1979). In addition to the traditional ten or so areas of these publications, recent efforts were made to delineate smaller map units (ironically using the title of "region" which is the designation for geographic size larger than area) of natural communities and/or landscapes under auspices of The Natural Heritage Policy Research Project through the Lyndon B. Johnson School of Public Affairs at the University of Texas, Austin (1978) and available "on line" through Texas Parks & Wildlife. This latter project is but the most recent of several studies into the natural resources of Texas. In this regard see for example the report, Texas Looks Ahead-- The Resources of Texas (University of Texas, 1944, pgs. 273-282). A side issue but an interesting lesson in politics was presented by these two reports. Former United States Presidents have ways of getting their names attached as memorials to things that were already being done or created with little or no benefit from the previous Chief Executive. LBJ was clearly a master of this situation. A similar case in point was the Cross Timbers National Grassland that was renamed the LBJ National Grassland even though it was President Franklin Delano Roosevelt and not Lyndon Baines Johnson who was responsible for creation of this part of the National Forest System. One of the most recent exercises in mapping of Texas "natural areas or regions" was the the multi-agency project that produced the map, Ecoregions of Texas (Griffith et al., 2004). Unfortunately (perhaps unavoidably) some the level III and level IV ecoregions were inconsistent with other (older but sometimes more precise) designations and delinations. For example, the Stockton Plateau Ecoregion (Level IV) in Griffith et al. (2004) does not coincide completely with the southern portion of the Stockton Plateau as a land form and geologic unit (see Figure 2 in Amos and Gelbach, 1988, p. 4).

1. Edwards Plateau live oak-grassland savanna- Texas Edwards Plateau, a section of the Great Plains physiographic province, has traditionally been treated as a vegetational or land resource area. However, it does not correspond closely to kinds of vegetation. The Edwards Plateau is a geologic unit. It is a single block of limestone existing as a stripped plain but this consist of several subregions, each supporting a different form or kind of vegetation. Here is the oak-juniper mixed prairie savanna. It consist of dominant live and post oaks along with such junipers as redberry cedar (Juniperus pinchotii) and blueberry, post, or Ashe cedar (J. ashei) and many grass species ranging from little bluestem (Andropogon scoparius= Schizanchyrium scoparium), Canada wildrye (Elymus canadensis), Texas cupgrass (Eriochloa sericea), plains lovegrass (Eragrostis intermedia) and green sprangletop (Leptochloa dubia) to buffalograss (Buchloe dactyloides), curly mesquite (Hilaria belangeri), and various gramagrasses including sideoats grama (Bouteloua curtipendula), blue grama (B. gracilis), hairy grama (B.hirsuta) tall grama (B. pectinata), and red grama (B. trifica). Vine mesquite (Panicum obtusum), several perennial threeawn species, and the ever-present cool-season Texas wintergrass are major grasses. Introduced and now naturalized forbs include red-stem filaree or storksbill. Typically there are always some actively growing forage species in this portion of the Edwards Plateau. Menard County, Texas. June. FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna). SRM 734 (Mesquite-Oak). Edwards Plateau Woodland Ecoregion, 30a (Griffith et al., 2004).

2. View of the Llano area or subregion of the Edwards Plateau (generally referred to as Llano Uplift)- This massive granite uplift is the famous Enchanted Rock. Rislind and Diamond (in Amos Gehlbach, 1988, p. 5) explained the uniqueness of this part of the Edwards Plateau: "The Llano Uplift is strinkingly different from the remainder of the Edwards Plateau. It is an intrusive outcrop of Precambrian granitic material". Vegetation is essentially the same as in the oak-juniper savanna unit except trees are often more dense with a greater component of mesquite and other woody plans such as the lianas of various grape (Vitus) species. Llano County, Texas. October. FRES No. 32 (Texas Savanna Ecosystem). K-78 (Mesquite-Oak Savanna). SRM 734 (Mesquite-Oak) variant. Edwards Plateau Llano Uplift Ecoregion, 30b (Griffith et al., 2004).

General Edwards Plateau, including Oak-Juniper Savanna and Lampasas Cut Plain

3.Tallgrass prairie on Lampasas Cut Plain- Prairie landscape and range plant community presented in this photograph was more typical of the Kansas Flint Hills and Oklahoma Osage Questas than the Texas Edwards Plateau, but as was described and explained in the introduction to the Edwards Plateau the Lampasas Cut Plain is part of the Great Plains and not the Central Lowlands physiographic province. Given that physiographic relations are second only to those of climate, range vegetation of the Lampasas Plain was most precisely or properly placed in the Edwards Plateau rather than in the more physiogonomically similar Cross Timbers and Prairies and/or Blackland Prairie vegetational (= land resource) areas. The analamous tallgrass prairie climax community (= potential natural vegetation) of the Lampasas Cut Plain contrast dramatically with the tree/shrub-mixed grass savanna of the rest of the Edwards Plateau. Floristic and vegetational distinctiveness of the example of virgin climax little bluestem-meadow dropseed grassland show above was introduced early in this series to emphasize the diversity of range vegetation within the Edwards Plateau and to show the botanical affinity of Edwards Plateau range types with those of the Texas Blackland Prairie and Cross Timbers and Prairies area. Affinity in species composition and structure was greatest between grasslands of Lampasas Cut Plain and Grand (= Fort Worth) Prairie. .The pristine tallgrass prairie shown here was actually more a mixture of both tallgrass and mid-grass species with shortgrass species also well-represented. Co-dominants were clearly little bluestem and meadow dropseed (Sporobolus asper var. drummondii= S. asper var hookeri= S. pilosus), but the midgrasses silver bluestem (Andropogon saccharoides= Bothriochloa saccharoides) and sideoats grama and the shortgrass hairy grama were obvious associates. Purple threeawn (Aristida purpurea) was also widely distributed. Other Sporobolus species were widespread on this range including purpleflower dropseed (S. clandestinus) and poverty dropseed (S. vaginaeflorus). Indiangrass (Sorgastrum nutans) was present in small proportions, but it served as an indicator species typical of tallgrass-dominated prairie communities. The major forb was elegant gayfeather (Liatris elegans) while annual broomweed (Gutierrezia draculoides), the second most common forb, gave the Compositae its usual domination of the forb category. With a range plant community in which tall-, mid-, and shortgrass species were well-represented this grassland resembled (to a degree) a mixed prairie typical of climax Great Plains grasslands in the Rolling Red Plains vegetational area, but dominance by tallgrass species and physiogonomy indicative of tallgrass vegetation clearly distinguished this as tallgrass (vs. mixed) prairie. This range was most likely in the high Good (possibly low Excellent) range condistion class based on the classic Dyksterhuis (1949) Soil Conservation Service model of range analysis. Lampasas County, Texas. October, autumnal aspect. FRES No. 39 (Prairie Grassland Ecosystem). K-66 (Bluestem Prairie). Variant of SRM 710 (Bluestem Prairie); the Bluestem-Dropseed rangeland cover type (SRM 708) is descriptive in title only as this latter is a semiarid cover type of sandy soils (Shiflet, 1994). Bluestem"Tall-Grass" Series of Plains Grassland biotic community of Brown et al., 1998). Limestone Cut Plain Ecoregion 29e (Griffith et al, 2004).

4. Edwards Plateau pristine range vegetation- This is the Edwards Plateau mixed prairie-live oak savanna. This form of the Edwards Plateau range ecosystem is obviously more grassland than shrubland. It should logically have been arranged under the Grassland and not the Shrubland Biome slides. It was placed here for consistency so as to keep all the Edwards Plateau examples together even though the Edwards Plateau Vegetation (= Land Resource) Area of Texas is a geologic-based and not a biological- or botanical-based unit. This placement is consistent also with the forest and range ecosystem descriptions of Garrison et al. (1977, ps. 39-41) who placed the Edwards Plateau range communities under the Texas Savanna Ecosystem, FRES No.32, which they arranged under Shrubland Ecosystems and not Grassland Ecosystems.  This “mint condition” example of the Edwards Plateau grassland–savanna was the vegetation described by John Leonard Riddell, a university professor and medical doctor, who was the first trained naturalist-scientist to visit and describe the Texas Edwards Plateau (Breeden, 1994, p.xi):

“The musquit (mesquite) tree now disappears and is replaced by live oak, post oak, etc. The country becomes more & more hilly … Land sparsely timbered, but no uninterrupted large prairies. Real thickets occur only in the canadas or ravines of water courses” (Riddel journal entry of 25 October, 1839 as edited by Breeden,1994, ps. 58-59).

This is mixed prairie with the dominant tallgrass species being little bluestem with Indiangrass and Canada wildrye the associates of the tallgrass prairie plants. Sideoats grama, vine mesquite (Panicum obtusum), silver bluestem, and Texas wintergrass (Stipa leucotricha) are dominant midgrass species while buffalograss, curly mesquite (Hilaria belangeri), hairy grama, red grama (Bouteloua trifida), and Texas grama (B. rigidiseta) are abundant on openings among the dominant bunchgrasses. Wrights and purple threeawn are present but relatively rare in this Excellent range condition class community. The dominant tree species is the scrub live oak or plateau oak (Quercus virginiana var. fusiformis= Q. fusiformis). Post oak is the associate while mesquite and juniper are widely scattered.  Note presence of sheep and the absence of a pronounced browse line even though oak leaves are palatable to sheep and the white-tail deer that are “thick as hops” in the Texas Hill Country. An example of excellent stewardship on a private ranch.  McCullough County, Texas. Late estival aspect, June. FRES No. 32 (Texas Savanna Ecosystem), mapped as K-77 (Juniper-Oak Savanna) or 78 (Mesquite-Oak Savanna), but this pristine range lacks the dual scurge of juniper and mesquite. SRM 734 (Mesquite-Oak). Edwards Plateau Woodland Ecoregion, 30a (Griffith et al., 2004).

5. Physiognomy of Edwards Plateau mixed prairie-live oak savanna range- Community scale view of the live oak phase of Edwards Plateau savanna. Dominant grass was little bluestem, in fact a little bluestem consociation with Indiangrass as associate species. Texas parks and Wildlife Kerr Wildlife Management Area, Kerr County, Texas. October. Autumnal aspect. FRES No. 32 (Texas Savana Ecosystem). K-77 (Juniper-Oak Savanna). SRM 734 (Mesquite-Oak). Edwards Plateau Woodland Ecoregion, 30a (Griffith et al., 2004).

6. Edwards Plateau mixed prairie-live oak savanna range community- Species composition of the live oak-dominated phase of Edwards Plateau savanna range. Texas Parks and Wildlife Kerr Wildlife Management Area, Kerr County, Texas. October. Autumnal aspect. FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna). SRM 734 (Mesquite-Oak). Edwards Plateau Woodland Ecoregion, 30a (Griffith et al., 2004).

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7. Edwards Plateau mixed prairie-oak savanna- Live oak was the dominant, almost exclusive, woody species except for post oak which was the associate woody species while little bluestem was the dominant understorey herbaceous species (Indangrass was associate herbaceous species) on this relict Edwards Plateau vegetation. Abundant regeneration of both oak species, but reproduction was greater for live oak which was the local dominant. Gillespie County, Texas. October. Autumnal aspect. FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna). SRM 734 (Mesquite-oak). Edwards Plateau Woodland Ecoregion, 30a (Griffith et al., 2004).

8. Edwards Plateau savanna range plant community- In this relict Edwards Plateau range vegetation the locally dominant live oak formed a canopy consociation while the understorey was dominated by little bluestem with Indaingrass as the associate. Both tallgrass species were conspicuous in foreground as were larger seedlings of live oak. Two other-- though infrequent-- woody species were the shrubs algerita, algarita, or algerita thorn (Berberis trifoliolata= Mahonia trifoliolata) and lime pricklyash or tickle-tongue (Zanthoxylum hirsutum). Relict vegetation, and at peak standing crop at end of a wet summer. Rare view all the way around. Enjoy while it last! Gillespie County, Texas. October. Autumnal aspect. FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna). SRM 734 (Mesquite-Oak). Edwards Plateau Woodland Ecoregion, 30a (Griffith et al, 2004).

9. Edwards Plateau savanna range at peak standing crop- Two scenes of the post oak-dominated phase of Edwards Plateau mixed prairie-oak savanna with dominant tallgrasses at hard seed phenological stage. Dominant understorey herbaceous species was little bluestem (pretty much a little bulestem consociation) with Indiangrass as associate. Live oak was the associate woody species. Pristine vegetation at end of a wet summer. Ultimate expression (climax plant community) of Edwards Plateau savanna range. Gillespie County, Texas. FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna). SRM 734 (Mesquite-Oak). Edwards Plateau Woodland Ecoregion, 30a (Griffith et al., 2004).

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10. Edwards Plateau savanna as the Commanche knew it- Pristine mixed prairie-oak savanna range with post oak and live oak the dominant and associate, respectively, woody species and little bluestem and Indiangrass the dominant and associate, respectively, herbaceous species of the understorey. Kerr County, Texas. October. Autumnal aspect. Tallgrass species in hard seed phenological stage. FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna). SRM 734 (Mesquite-oak). Edwards Plateau Woodland Ecoregion, 30a (Griffith et al., 2004).

11. Relict Edwards Plateau range plant community- Climax mixed prairie-oak savanna with post oak the dominant and live oak the associate woody species and little bluestem the dominant and Indiangrass the association herbaceous species. "It does get any better than this". Textbook species compostiton of the more mesic and northern portion of Texas Edward Plateau. Gillespie County, Texas. October. Autumnal aspect; peak standing crop of understorey. FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna). SRM 734 (Mesquite-Oak). Edwards Plateau Woodland Ecoregion, 30a (Griffith et al., 2004).

12. Inside climax Edwards Plateau savanna range- Post oak-dominated phase of one of the more mesic and northern parts of the Edwards Plateau (live oak was the associate woody species). No mesquite or juniper in this relict stand. It was range like this that once made the Edwards Plateau, the fabled "Texas Hill Country" a fabulous and famous grazing ground for numerous species of livestock and wildlife. Note dense colony of Indiangrass in right foreground. Scrub tree form of post and live oaks was typical of growth habit of these species in this range type. Gillespie County, Texas. October. Autumnal aspect.

13. Edwards Plateau mixed prairie- Natural grassland expressions (subtypes) of range are relatively rare in the Edwards Plateau being mostly restricted (as was explained above) to the Lampasas Cut Plain portion of this Texas vegetational or land resource area of Texas. This is expecially the situation in post-white man times with ever-increasing brush invasion. The relict range vegetation presented here was a mixed (tall-, mid-, and shortgrass species) prairie form of grassland that occurred within a general live oak-grass savanna visible in the background. The local range plant community shown in these two photographs consisted of little bluestem as the major tallgrass species with Indiangrass, Canada wildrye and various perennial dropseeds being other native tallgrass species and Johnsongrass as a naturalized tallgrass. Midgrasses included silver bluestem, sideoats grama, Texas wintergrass, and Texas cupgrass. Major shortgrass species were hairy grama, curly mesquite, and buffalograss. The most common shrub was soapweed (Yucca glauca) and grassland pricklypear (Opuntia macrorhiza). There were almost no forbs: annual broomweed (Gutierrezia dracunculoides) was the most abundant forb species. Menard County, Texas. October (under gray sky midway through an early norther); peak standing crop. FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna). A grassland variant (form) of SRM 733 (Juniper-Oak). Edwards Plateau Woodland Ecoregion, 30a (Griffith et al., 2004).

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14. Edwards Plateau live oak-cedar savanna- Plateau live oak and post, blueberry, or Ashe juniper (usually called known as post etc. cedar) formed a prominent layer of low trees and/or shrubs on an otherwise mixed prairie grassland of mostly mid- and shortgrass species (primarily sideoats and hairy gramas, Texas wintergrass, curly mesquite, and buffalograss with substantial though lower cover of little bluestem, green sprangletop, and Texas cupgrass). This range had been useed for many years (decades) by sheep, goats (Angoras), and whitetail deer such that there were relatively few forbs in the herbaceous understorey. In fact, this small ruminant range had been so heavily browsed as to result in a conspicuous browseline, a situation known as "highlining". The major (and about the only) shrub species with reach of a goat or deer standing on his hind legs was some subspecies of common Texas, Engelmann's, or Lindheimer's pricklypear (Opuntia engelmannii= O. lindheimeri: nomenclatural treatment of this Opuntia group has been a long-running taxonomic feud skirmish that may never be settled). This range was in Good range condition class with less cover and density of tallgrass species (aconversely, more of mid- and shortgrass species) than in climax vegetation. Palatability of Ashe juniper (which is substantially greater than that of Juniperus pinchotii) was obvious from the two highlined trees featured in this slide. Schleicher County, Texas. October, and a very wet one; autumnal aspect. FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna). SRM 733 (Juniper-Oak). Mixed Grass-Scrub Series 143.14 (Brown et al., 1998, p. 40). Edwards Plateau Woodland Ecoregion, 30a (Griffith et al., 2004).

15. Live oak-mixed prairie savanna- Sideoats grama was dominant, but there was also high cover and density of silver bluestem, hairy grama, buffalograss, curly mesquite, Texas wintergrass, and various perennial dropseeds. These were the major species except in herbaceous understorey of live oak mottes where Texas cupgrass, Canada wildrye, Texas wintergrass, and green sprangletop were local dominants depending on microsite. Some subspecies of Texas, Engelmann's, or Lindheimer's pricklypear was the associate shrub. This was strictly cattle and whitetail deer (the only ungulate species) range resulting in more live oak biomass at browse height (reflecting relatively low degree of use of live oak by cattle). Also at the relatively low or conservative stocking rate on this range there had been very little grazing beneath live oaks such over time the more palatable tallgrass and midgrass species came to dominate the understorey of live oak mottes. This was a textbook example of proper degree of use (generally the most important of the Four Cardinal Principles of Range Management) and consequent wise use management. Range condition class was high Good to low Excellent on this Shallow range site. Schleicher County, Texas. October of a wet late summer and early autumn (which enhanced expression of species composition of this range). FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna). SRM 733 (Juniper-Oak). Mixed Grass-Scrub Series 143.14 (Brown et al., 1998, p. 40). Edwards Plateau Woodland Ecoregion, 30a (Griffith et al., 2004).

16. "Summary" (composite) species composition of a plateau live oak-mixed prairie savanna- An example of Edwards Plateau vegetation on a Shallow range site that was part of a cattle and wihtetail deer range used conservatively (fairly low stocking rate) in a wet late summer-early autumn. Major grass species (in approximate relative composition) were sideoats grama, curly mesquite, silver bluestem, hairy grama, Texas wintergrass, Texas cupgrass, and perennial dropseeds. Little bluestem and Indiangrass (potential associate or dominant grasses) were present in small amounts, but invaders like perennial threeawns and red grama occurred at much smaller proportions. Texas or Engelmann pricklypear was the associate shrub to live oak. Forbs were almost non-existant suggesting that at one time this range had been stocked heavily with sheep and goats. Range condition class was Good and degree of use was light. Students should "read sigh" and carefully observe that live oak foliage was regenerating on previously "highlined" (having high browse heights) oaks. All-in-all: sound, wise use management with subsequent restoration of range resources. Schleicher County, Texas. October of a wet late summer and early autumn (which enhanced expression of species composition of this range though it certainly did not determine botanical make-up). FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna). SRM 733 (Juniper-Oak). Mixed Grass-Scrub Series 143.14 (Brown et al., 1998, p. 40). Edwards Plateau Woodland Ecoregion, 30a (Griffith et al., 2004).

17. Beneath the live oaks- Herbaceous understorey of a motte of plateau live oak on lightly stocked cattle and deer range was dominated by Texas cupgrass, Canada or nodding wildrye, Texas wintergrass, silver bluestem, and sideoats grama (in about that relative order) with conspicuous but considerably less cover of green sprangletop and little bluestem. Schleicher County, Texas. October of a wet late summer and early autumn (which enhanced--but did not determine--the expression of species composition of this range). FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna). SRM 733 (Juniper-Oak). Mixed Grass-Scrub Series 143.14 (Brown et al., 1998, p. 40). Edwards Plateau Woodland Ecoregion, 30a (Griffith et al., 2004).

18. Still under the live oaks- Sward of herbaceous layers of the plateau live oak motte preented in the immediately preceding photograph. In this slightly different "photo-plot" the major species were (in estimated approximate order) Texas cupgrass, Canada or nodding wildrye, Texas wintergrasss, and green sprangletop with lesser cover of sideoats grama, silver bluestem, and, with least cover, little bluestem. On this Shallow range site, this species make-up constituted Good range condition class. Degree of use was extremely light which was a combination of abundant recent rains and low (conservative) stocking rate. Obviously there is much truth in the adage that abundant and advantageously timed rainfall can compensate for some management sins, but this is, of course, limited. All the rain in the world could not explain the botanical composition of this range. Edwards Plateau savanna vegetation. Good stewartship explained this gem of Edwards Plateau savanna vegetation. Schleicher County, Texas. October, autumnal aspect. FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna). SRM 733 (Juniper-Oak). Mixed Grass-Scrub Series 143.14 (Brown et al., 1998, p. 40). Edwards Plateau Woodland Ecoregion, 30a (Griffith et al., 2004).

19. Typical Edwards Plateau mixed prairie-oak-juniper savanna range- In the more central portion of the Edwards Plateau the mid- and shortgrass species are more prominent while the tallgrass species are less common than in the more northern and eastern portions. One of the most influencial environmental variables of the Edwards Plateau Region is frequent severe drought. This is exacerbated by the shallow, stony soils overlying the granite or limestone bedrock. An appropriate caption for this slide would have been “A Dry Spring in the Edwards Country” to describe the protracted winter-drought dormancy phase seen here. This is May on a Good range condition class range grazed by cattle, sheep, goats, and white-tail deer. Little bluestem, silver bluestem, sideoats grama, curly mesquite, buffalograss, and several grama species make up a mixed prairie undertstory to the savanna woody layer of scrub live oak or plateau oak with scattered juniper trees. The range should be green this time of year, but all grass species are either still dormant or, in the instance of the cool-season species like Texas wintergrass, recently browned upon completion of their yearly cycle. The large green clumps are sacahuiste (Nolina texana) which if eaten in large enough quantities can cause secondary photosensitization (skin lesions due to liver damage) and kidney damage.   This is a study pasture in a stocking rate trial on the famous Texas A&M University System Sonora Experimental Range (Edwards County, Texas). It has been stocked for the past five years at 32 Animal Units per Section (640 acres) which is regarded as moderate stocking for this range site. Note the moderate highlining of the live oaks. At first flush this rangeland looks to be in “tough shape” due to drought and a fairly uniform and relatively “short”, even “close”, degree of use. This is a case where “looks are deceiving”. The species composition includes high levels of little and silver bluestem (the portion with grass clumps at left midground extending across in front of the center clumps of live oaks) while the shorter-cropped grasses in the foreground are dominated by sideoats grama and curly mesquite with relatively low proportions of invaders like red and Texas gramas. This is an example of proper use management that allows for adequate ground cover (against the torrential rains that often break a drought) of decreaser and increaser species even after prolonged drought.

“In Texas the savy rancher is either in a drought or preparing for one”.                                                                                --- An old and very wise Texas saying. FRES No. 32 (Texas Savanna Ecosystem), K-77 (Juniper-Oak Savanna), SRM 734 (Mesquite-Oak). Mixed Grass-Scrub Series 143.14 (Brown et al., 1998, p. 40). Semiarid Edwards Plateau Ecoregion, 30d (Griffith et al., 2004).

20. Typical scene of Edwards Plateau range- Common use (Rambouillet sheep, Boer goats, and whitetail deer were the major species) of a live oak-juniper mixed prairie savanna in central Edwards Plateau. On this Fair condition range tallgrasses like little bluestem and Indiangrass were extremely limited, some midgrasses like silver bluestem were also uncommon while others like sideoats grama and plains lovegrass were locally abundant, and shortgrasses (curly mesquite, buffalograss, hairy grama) were generally dominant. This small trap was close to ranch headquarters and frequently received heavy use. Shrubs present at relative covers of invader status included Texas, Englemann or Lindheimer pricklypear; agarito; and honey mesquite. Forb invaders were western ragweed (Ambrosia psilostachya) and silverleaf nightshade (Solanum elaeagnifolium). There was also something of a high browse line, though nothing like the 'highlined" browse so often present on Edwards Plateau ranges that are browsed by goats, deer, sheep, cattle, sundry exotic ungulates (and often God alone knowns what else). Texas A&M University Sonora Experiment Station, Edwards County, Texas. October, autumnal aspect. FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna). SRM 733 (Juniper-Oak). Mixed Grass-Scrub Series 143.14 (Brown et al., 1998, p. 40). Semiarid Edwards Plateau Ecoregion, 30d (Griffith et al., 2004).

21. About as close to pristine as it gits nowadays- Live oak-mixed prairie savanna with a botanical composition at (or close to) climax. Dominant grasses were silver bluestem and sideoats grama with plains lovegrass, Texas wintergrass, Texas cupgrass, cane bluestem (Andropogon barbinodis= Bothriochloa barbinodis var. barbinodis), little bluestem, and dropseed species also major grasses. Curly mesquite and buffalograss were much less plentiful than on adjoining ranges. There was relatively little threeawn and that was purple threeawn (Aristida purpurea complex). Occasional plants of King Ranch bluestem (Andropogon ischaemum= Bothriochloa ischaemum var. songarica) were present, but much more limited than was typical for this local area. The most common forb was redstem filaree (Erodium cicutarium). This was in contrast to abundant cover and density of western ragweed and silverleaf nightshade on adjacent ranges. There were scattered plants of the composite slender greenthread (Thelesperma simplicifolium). The Excellent condition class range presented in these two (and the succeeding plus two later photographs) was less than 300 yards from the Fair condition range in the immediately preceding slide. Texas A&M University Sonora Experiment Station, Edwards County, Texas. October, autumnal aspect. Peak standing crop for this range plant community. FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna). SRM 733 (Juniper-Oak). Mixed Grass-Scrub Series 143.14 (Brown et al., 1998, p. 40). Semiarid Edwards Plateau Ecoregion, 30d (Griffith et al., 2004).

22. Edwards plateau savanna in top form- Another view of the climax live oak-juniper-mixed prairie savanna presented immediately above. Physiogonomy and structure of this multi-layered range vegetation was obvious with tallgrasses represented by little bluestem while silver bluestem, cane bluestem, sideoats grama, plains lovegrass, and Texas wintergrass were major midgrasses with curly mesquite, buffalograss, and hairy grama being the major shortgrasses. There were occasional plants of the invader grasses King Ranch bluestem and purple threeawn and increaser green sprangletop. The desirable naturalized Mediterranean forb, redstem filaree or stork's bill, was present as was the native invader, western ragweed. There was low density of naturalized Mediterranean annual grasses (Bromus spp.). Texas A&M University Sonora Experiment Station, Edwards County, Texas. October, autumnal aspect. Peak range biomass. FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna). SRM 733 (Juniper-Oak). Mixed Grass-Scrub Series 143.14 (Brown et al., 1998, p. 40). Semiarid Edwards Plateau Ecoregion, 30d (Griffith et al., 2004).

23. Multi-species carpet of grass- Sward of the climax Edwards Plateau mixed prairie savanna shown in the three immediately preceding photographs. This Excellent condition range had three prominent layers of grass: 1) tallgrass represented mostly by little bluestem, 2) midgrass element consisting mostly of silver bluestem, sideoats grama, plains lovegrass, Texas wintergrass, and cane bluestem, and 3) shortgrass composed of curly mesquite, buffalograss, and hairy grama. Forbs were limited (likely resulting from grazing by sheep, goats, and deer) with the naturalized annual redstem filaree or stork's bill the major species. The very restricted invaders included purple threeawn, King Ranch bluestem, western ragweed, and silverleaf nightshade. Texas A&M University Sonora Experiment Station, Edwards County, Texas. October, autumnal aspect. Peak standing crop. FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna). SRM 733 (Juniper-Oak). Mixed Grass-Scrub Series 143.14 (Brown et al., 1998, p. 40). Semiarid Edwards Plateau Ecoregion, 30d (Griffith et al., 2004).

24. Some of a lot- This photographic quadrant of the sward of the climax Edwards Plateau savanna range shown in the four slides immediately above included silver bluestem, curly mesquite, and buffalograss at peak standing crop and early growth redstem filaree. Multi-layers of the herbaceous part of this range type were distinct. Texas A&M University Sonora Experiment Station, Edwards County, Texas. October, autumnal aspect. Peak standing crop. FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna). SRM 733 (Juniper-Oak). Mixed Grass-Scrub Series 143.14 (Brown et al., 1998, p. 40). Semiarid Edwards Plateau Ecoregion, 30d (Griffith et al., 2004).

25. Edwards Plateau savanna as it is best known- This arch-typical scene of oak-juniper mixed prairie savanna had a rougly 50:50 mix of redberry or Pinchot cedar (juniper) and blueberry or post or Ashe cedar (juniper) along with plateau live oak (as co-dominant) and honey mesquite that formed an arboreal layer while Texas, Lindheimer, or Engelmann pricklypear and agarito along with an occasional devil's head or cow crippler cactus (Echinocactus texensis) comprised a lower shrub layer. Both of these woody layers occurred as local individuals or small, scattered stands in a mixed prairie of three prominent herbaceous layers each dominated by a few to several species of native grassses. These grasses were primarily warm season perennials, but Texas wintergrass represented cool season perennials while cool season annual grasses included the naturalized Mediterranean species, Japanese chess (Bromus japonicus) and cheatgrass (B. tectorum), as well as the native annual, little barley (Hordeum pusillum). Annual grasses were more common on this range than on the range at or approaching the climax state in preceding slides. Naturalized warm season grasses were limited to the relatively scarce Johnsongrass and King Ranch bluestem. In context of Landscape Ecology live oak mottes and cedar stands were patches in a matrix of mixed prairie. Texas A&M University Sonora Experiment Station, Edwards County, Texas. October, autumnal aspect. Peak standing crop stage. FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna). SRM 733 (Juniper-Oak). Mixed Grass-Scrub Series 143.14 (Brown et al., 1998, p. 40). Semiarid Edwards Plateau Ecoregion, 30d (Griffith et al., 2004).

26. Praise the Lord (especially for recent rains) and pass the drip tourch- Edwards Plateau live oak-juniper mixed prairie savanna invaded by Pinchot or redberry and Ashe or post junipers nine months following a winter (January) prescribed burn. Even the relatively cool winter burn top-killed almost every cedar (juniper) and all but the largest honey mesquites on this range (note two mesquites in second slide). This pasture had been grazed throughout the plant-growing seasons subsequent to the prsecribed fire. On this specific range tallgrass species like little bluestem, Indiangrass, and green sprangletop were relatively rare except for dropseed species so that the range plant community was primarily one of midgrasses (sideoats grama, silver bluestem, Texas wintergrass, plains lovegrass, common windmillgrass (Chloris verticillata), cane bluestem, and purple threeawn in that rough order) and shortgrasses (curly mesquite, buffalograss, hairy grama. There were scattered plants of the exotic King Ranch bluestem and Johnsongrass. Woody plants in addition to live oak, cedar, and mesquite included the cactus species, Texas or Engelmann pricklypear and tasajillo (Opuntia leptocaulis), agarito, and Texas persimmon. Tasajillo, including the largest plants, had been topkilled by the prescribed burn, but many of the larger clumps of pricklypear had most shoots spared. Also, individual plants of the low-growing Devil's head or cow (horse) crippler cactus had been passed over. The major forbs were silverleaf nightshade and western ragweed with redstem filaree and Croton spps. including Texas croton (C. texensis). In the first photograph herbaceous vegetation in the lighter green (yellowish-green) patch in the foreground was a mixture of curly mesquite and buffalograss, the former of which had somewhat greater cover. Darker green herbaceous layer in background was a "duke's mixture" of sideoats grama, Texas wintergrass, silver bluestem, dropseeds, plains lovegrass, hairy and red grama, and purple threeawn. Little bluestem was the least abundant grass followed by naturalized King Ranch bluestem. There were also individuals of Mediterranean annual bromegrasses, probably both cheatgrass and Japonese brome, in the interspaces among the mid-height bunchgrasses. The second photograph also displayed the patchy arrangement or structure of the shortgrass and midgrass components, perhaps more graphically than the contrasts shown in the first potograph. Frequently there are local grass communities (small-scale mixed species groups on microsites) on Edwards Plateau mixed prairie that include numerous grass species of various heights at maturity, but the more common organization is presence of tall-, mid-, and shortgrass species as segregated vegetational units (eg. a patch of curly mesquite and buffalograss; a separate local assemblage of sideoats grama, silver bluestem, and plains lovergrass). In foreground of second slide a patch of midgrasses included sideoats grama, perennial dropseeds, plains lovegrass, and common windmillgrass. In left midground there was a patch of curly mesquite and buffalograss similar to that in foreground of the first of these two slides. It seemed likely that the patch-by-patch arrangement or architecture of range plant communities on Edwards Plateau mixed prairie savanna reflected competition (eg. for light), adaptation to microsite variables (eg. edaphic features such as soil depth or stoniness), past spot grazing (perhaps localized overuse or overgrazing), or simply chance (ie. the Gleasonian view of plant communities). The second slide also illustrated selective "browsing" (defoliation) by fire. The larger mesquite at far right lost some lower limbs to the prescribed fire, but otherwise the existing shoot (tree above ground) survived because meristematic tissue was high enough above flames to avoid the thermal death point (usually regarded as 140 degrees Fahrenheit or 60 degrees Centigrade). By comparison, the smaller mesquite in center foreground was totally topkilled and had resprouted prolifically from the vast root system so typical of this species. This is a good example of the hard-learned fact that sometimes a larger, single-stemed mesquite has less foliar cover and shades less ground (thus perhaps causing less loss in forage production) than a smaller, multi-stemmed, shrubby mesquite. In such circumstances, a cool prescribed fire (as in a winter burn) that "flags" rather than topkills mesquite may be superior for brush control and general range improvement. This situation was further demonstrated in another photograph of this same range below (seven slides sebsequently). Other management and ecological perspectives must also be considered of course, including other brush species. On the range shown here the prescribed fire was needed primarily for reduction in cover and density of two Juniperus species as well as other miscellaneous brush plants like honey mesquite and tasajillo. Results of prescribed firing of this specific Edwards Plateau range were considered further below. Texas A&M University Sonora Experiment Station (pasture 8 Southeast), Edwards County, Texas. October, autumnal aspect. FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna). SRM 733 (Juniper-Oak). Mixed Grass-Scrub Series 143.14 (Brown et al., 1998, p. 40). Semiarid Edwards Plateau Ecoregion, 30d (Griffith et al., 2004).

27. Representative samples of sward- Two photo-plots of the herbaceous layers of the oak-juniper mixed prairie savanna range introduced above. Peak standing crop of the herbaceous component of the range plant community on this grazed range nine months after a winter (January) prescribed burn. The first photograph was a composite sample of the herbaceous--mostly grass--component of this Edwards Plateau nine months after a wintr (January) prescribed burn. Grass species included curly mesquite, sideoats grama, buffalograss, hairy grama, red grama, and purple threeawn. Sward shown in the second photograph was dominated by plains lovegrass with sideoats grama, common windmillgrass, curly mesquite, Texas wintergrass, and hairy grama represented. Most common forb in both photo-quadrants was silverleaf nightshade. Texas croton and redstem filaree were also present. Photographs were taken at peak standing crop for herbaceous component of the range plant community in an extremely wet late summer-early autumn period (about six inches of rain in the four weeks immediately preceding photographs). Texas A&M University Sonora Experiment Station (pasture 8 Southeast), Edwards County, Texas. October, autumnal aspect. FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna). SRM 733 (Juniper-Oak). Mixed Grass-Scrub Series 143.14 (Brown et al., 1998, p. 40). Semiarid Edwards Plateau Ecoregion, 30d (Griffith et al., 2004).

28. Patch of shortgrass sward- Photo-quadrant of a local microsite of oak-juniper mixed prairie savanna consisting of two shortgrass species: 1) buffalograss, shorter plants in foreground and 2) curly mesquite, somewhat taller plants in background. This sample of one herbaceous layer of this range vegetation represented a microenvironment that in the concept of Landscape Ecology was a localized patch in the overall matrix of shrub and tree-mixed (tall-, mid-, and shortgrass species) prairie. This layer of native vegetation was photographed on a range that had been burned by prescription nine months previously, grazed during the plant-growing season, and recieved about six inches of rain in the immediately preceding four weeks. Warm-season grasses and range vegetation overall was at peak standing crop and seed-ripe to seed-shatter stages. Sward is the term applied to the layer(s) of herbaceous plants, especially of grasslands and savannahs. Sward refers to both above- and belowground parts or zones. Texas A&M University Sonora Experiment Station (pasture 8 Southeast), Edwards County, Texas. October, autumnal aspect. FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna). SRM 733 (Juniper-Oak). Mixed Grass-Scrub Series 143.14 (Brown et al., 1998, p. 40). Semiarid Edwards Plateau Ecoregion, 30d (Griffith et al., 2004).

29. Stewart stand-by of the Texas plains and plateaus- Sward of curly mesquite on the same range that had been treated by a cool winter (January) prescription burn nine months previously and that was featured in this series of slides. Curly mesquite is one of the major shortgrass species of the Southern Great Plains (of which physiographic province the Edwards Plateau is a section). Hitchcock and Chase (1950, p. 485) stated matter-of-factly: "Curly mesquite is the dominant 'short grass' of the Texas plains". These revered agrostologists were not specific as to the ecological status of curly mesquite as "the dominant". The consensus of scientific authority and the traditional interpretation of this species on most range sites has been that it becomes a major or dominant species under natural disturbances like drought or mismanagement of ranges, especially overgrazing. The Soil Conservation Service range site descriptions have almost invariably classified curly mesquite as an increaser or invader, again depending on range site. This conclusion was aptly stated in the Phillips Petroleum Company (1963, p. 43) booklet: "Curlymesquite has increased and invaded ranges where better grasses were killed out by abusive grazing". In revision of this work by Nicholson (Fort Hays State University, 2006, p. 49) specified: "This grass persists under heavy grazing but can be killed out by excessive grazing". It seemed that generally speaking curly mesquite fit the definition of an increaser, but as with other species ecological status varies by range site (ie. is range site-specific). Texas A&M University Sonora Experiment Station (pasture 8 Southeast), Edwards County, Texas. October, peak standing crop.

30. Curly mesquite (Hilaria belangeri)- This stoloniferous sod-former is typically one of two major shortgrass species on mixed prairie savanna ranges in the Edwards Plateau. Buffalograss is the other--and often--codominant shortgrass. Both of these species are better adapted to "heavier" (more clayey) soils. They increase with heavy grazing and protracted drought (before they in turn are displaced by less palatable invader and, often, deeper-rooted species). Texas A&M University Sonora Experiment Station (pasture 8 Southeast), Edwards County, Texas. October, peak standing crop and grain-shatter phenological stage.

31. What blessings prescribed fire hath wrought- A relatively cool prescribed burn in winter (January) topkilled most woody plants on this live oak-juniper mixed prairie savanna range in the central Edwards Plateau. Larger trees of plateau live oak and honey mesquite were either unaffected or minimally affected (eg. lost only lowermost limbs or buds). An example of this selective defoliation of fire on mesquite was presented previously (seventh slide preceding these photographs) in a description of this range type. In these two slides dramatic impacts of a winter prescribed burn were presented in regards to fire as a management tool to preserve Edwards Plateau savanna range by control and/or prevention of invasion by native woody plants that otherwise would proliferate to unnaturally excessive cover and density so as to become noxious range shrubs or trees (ie. brush). Prescribed fire is human manipulation of what is one of Nature's own forms of brush control. In fact, with possible exception of graqzing/browsing, fire is probably the most important and widespread natural phenomenon functioning to retard development of natural grassland and savanna vegetation toward dominance by trees and shrubs (ie. Mother Nautre's own choice for woody plant management). In the first of these two slides several mesquites of shrub form and size were topkilled by fire and sprouted profusely over the nine months following the prescribed burn. Conversely, two larger mesquites of small tree-size and shape (single trunk) shown in this photograph were less impacted by the prescribed fire (one mesquite at far right midground in front of topkilled mesquite scrub; another mesquite tree in center background). Various grass species that were generally identifiable in this first photograph based on color, shape, and/or size were abundant at peak standing crop and following abundant rains in the late summer-early autumn seasons. The perennial broadleaf herb, silverleaf nightshade, was conspicuous in the herbaceous understorey of this fired range. Silverleaf nightshade was the most common forb at this season. Many beautifully torched and scourched cedars were visible in the background. The second of these slides included topkilled or completely dead (wishful thiking perhaps) individual plants of tasajillo cactus (large, multistemmed shrub in left center), agarito (far left foreground, resprouting), two redberry or Pinchot juniper (both resprouting), and, arched around and framing the foremost juniper, honey mesquite. Grasses in the understorey included plains lovegrass, Texas wintergrass, curly mesquite, buffalograss, sideoats grama, purple threeawn, and silver bluestem. At far left background was a small stand of juniper and mesquite that had been missed by the prescribed fire. Texas A&M University Sonora Experiment Station (pasture 8 Southeast), Edwards County, Texas. October, autumnal aspect. FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna). SRM 733 (Juniper-Oak). Mixed Grass-Scrub Series 143.14 (Brown et al., 1998, p. 40). Semiarid Edwards Plateau Ecoregion, 30d (Griffith et al., 2004).

32. Pals on an Edwards Plateau range- Growth of range plant species nine or ten months after a cool winter (January) prescribed burn on an Edwards Plateau live oak-juniper-mixed prairie savanna. Sideoats grama, State Grass of Texas, (center, taller grass) was accompanied by curly mesquite (immediate left foreground) and, in front and slightly to right-of-center of sideoats grama, cow-crippler or Devil's head cactus (Echinocactus texensis). All warm-season grasses on this range had apparently benefitted from the prescribed burn while cool-season grasses and forbs appeared to have been mostly, if not wholly, uninfluenced by the cool fire. As shown immediately above and below this photograph most woody plants except large live oak and mesquite were either topkilled or completely killed by prescirbed burning. Flames of the fire passed over the cow-crippler cactus before the heat from flames reached the thermal death point (usually a temperature of about 60° Celsius or 140 ° Fahrenheit)). Unlike most other shrubs on this range, the shoot of this cow-crippler cactus survived the prescribed fire. Wind-blown racemes of sideoats grama illustrated the phenomenon of anemochory (= aerochory), wind dispersal of plant propagules (pollen and spikelets in case of this grass species). Texas A&M University Sonora Experiment Station, Edwards County (pasture 8 Southeast), Texas. October, autumnal aspect. FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna). SRM 733 (Juniper-Oak). Mixed Grass-Scrub Series 143.14 (Brown et al., 1998, p. 40). Semiarid Edwards Plateau Ecoregion, 30d (Griffith et al., 2004).

33. Two paired comparisons of response to fire- One blueberry, post, or Ashe juniper and one redberry or Pinchot juniper were shown side-by-side in two locations to provide a "replicated" comparison of the two species' different responses to fire. In both "replications" redberry or Pinchot cedar had resprouted while blueberry or Ashe cedar had not resprouted but instead had been killed (totally dead, both shoot and root). Responses of both plants of both species was the usual or typical species-specific response. Redberry juniper is one of the few coniferous trees in North America that has capacity for coppicing or sprouting (resprouting from stumps, rootcrowns, or other meristematic tissue). In the first slide blueberry cedar was on the left and redberry juniper on the right; in second slide blueberry juniper was to the right while redberry cedar was to the left. On both comparison plots herbaceous species (mostly mid- and shortgrasses; main forbs were silverleaf nightshade and Texas croton) had obviously benefitted from the prescribed burn. Texas A&M University Sonora Experiment Station (pasture 8 Southeast), Edwards County, Texas. October, autumnal aspect. FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna). SRM 733 (Juniper-Oak). Mixed Grass-Scrub Series 143.14 (Brown et al., 1998, p. 40). Semiarid Edwards Plateau Ecoregion, 30d (Griffith et al., 2004).

34. Setback- At least the prescribed winter (January) burn done nine months prior to these two shots topkilled these two redberry or Pinchot junipers. Both plants had sprouted from the bulbous lignotuber that is an obvious natural selection adaptation of this species to severe defoliation such as that by fire.Unfortunately, these two individual plants were not completely killed. They were severely injured and aboveground (shoot) growth of a considerable number of yedars (growing seasons) was killed. The second photograph showed details of stump sprouting or coppicing from the belowground (right below land surface) lignotuber present in this sprouting gymnosperm. With repeated prescribed burning Pinchot cedar can be controlled and topgrowth (growth and development of shoot) held to that many season's of growth. Repeated prescribed burning could be scheduled frequently enough to prevent seed formation and dispersal of this resprouting conifer. It was also obvious that herbaceous species (short- and midgrasses, silverleaf nightshade) were not severely damaged-- if at all--by prescription burning. Major grasses and forbs were perennials, but there were seedlings of Mediterranean annual grasses (mostly Bromus japonicus and/or B. tectorum) as well as redstem filaree or stork's bill in the green vegetation of this fired range which had been grazed during the previous growing season. Texas A&M University Sonora Experiment Station (pasture 8 Southeast), Edwards County, Texas. October, autumnal aspect. FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna). SRM 733 (Juniper-Oak). Mixed Grass-Scrub Series 143.14 (Brown et al., 1998, p. 40). Semiarid Edwards Plateau Ecoregion, 30d (Griffith et al., 2004).

35. A survival characteristic of a range plant and an unfortunate feature for brush-fighting rangemen- Redberry juniper readily resprouts from meristematic tissue at both basal parts of trunk (stump) and higher parts of trunk and limbs/branches. Such meristematic tissue would probably be described as lateral meristems or, perhaps, intercalary meristems.This evolved survival adaptation to fire was all too evident in redberry cedar that had resprouted profusely over course of nine months following a prescribed burn in January. Shown in these two photographs were examples of branching or resprouting from lateral meristems on branches of redberry cedar on the same Edwards Plateau mixed prairier-live oak-cedar savanna range that was featured immediately above. Second slide presented details of branch sprouting. While prescribed burning appeared to be essential for maintenance of the herbaceous components (layers) of Edwards Plateau vegetation--indeed, of various Edwards Plateau range ecosystems and the natural landscape--such range fires are selective so as to greatly reduce if not eliminate the nonsprouting Ashe or post cedar shifting the competitive advantage to Pinchot or redberry cedar. Continued use of prescribed fire, that is necessary for preservation or restoration of native Edwards Plateau range vegetation, unfortunately results in greater absolute and relative cover of redberry juniper. Such phenomenon was readily apparent on this specific range, and there was no readily solution for this shift in species other than more expensive mechanical and chemical brush control practices. Ironically it is Ashe juniper that is the more palatable (mostly to deer and goats) of these two species. As such biological control by ungulates seemed of limited application. Texas A&M University Sonora Experiment Station (pasture 8 Southeast), Edwards County, Texas. October.

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36. Edwards Plateau range as the Tonkawa and, later, Lipan-Apache knew it-Two exterior or ecosystem-scale views of climax (or near climax) plateau live oak-mixed prairie savanna of the central, semiarid Edwards Plateau. This range had been completely--or nearly so--restored to botanical composition and structure of pre-Columbian, potential natural vegetation (as best estimated by vegetation scientists.). Range improvement practices consisted of intensive individual plant treatment of noxious woody species (= brush) like post or Ashe juniper, redberry or Pinchot juniper, honey mesquite, pricklypear, tasajillo, agarito, Texas persimmon, soapweed yucca, and whitebrush in conjuction with proper grazing management. Brush control by mechanical (primarily bulldozer and hand tools) methods with local burning, and with minimum soil disturbance, coupled with deferment of grazing and subsequent light stocking rate permitted range restoration to the virgin vegetation or perhaps to seral stage just below climax. Some range scientists might conclude that for pristine vegetation on this range site (Low Stony Hills, East) there should have been relatively more than the small cover of such decreasers as little bluestem, Indiangrass, Canada wildrye, and even rare representatives of big bluestem .This rangeman did not share that interpretation for this particular range environment (ie. this combination of edaphic, climatic, topographic features). High cover, density, and biomass--both absoultely and relatively--of sideoats grama, plains lovegrass, sideoats grama, green sprangletop, Texas cupgrass, silver bluestem, and cane bluestem, along with the proportions of little bluestem and Indiangrass plus the species diversity of such other native grasses as curly mesquite, buffalograss, Texas wintergrass, and tall dropseed (Sporobolus asper) along with species of large, native perennial forbs including copper or narrowleaf globemallow (Sphaeralcea angustifolia) and orange daisy (Zexmenia hispida= Wedeelia hispida) clearly showed this to be a superb example of semiarid Edwrds Plateau savanna. Other increaser or invader grasses included other perennial dropseeds, common windmillgrass, hairy and red gramas, and purple threeawn. Mini-editorial (author's opinion)- This range student disagreed with range site descriptions (Soil Conservation Service) and ecological site descriptions (Natural Resources Conservation Service) as to relative importance of tall grass species, especially big bluestem and Indiangrass, in climax range vegetation of central and western portions of the Texas Edwards Plateau. In this author's view, parts of some of these site descriptions made the potential natural vegetation on shallow sites of the Edwards Plateau (eg. Low Stoney Hills, Adobe Hills) sound more like humid or subhumid Flint Hills tallgrass prairie than semiarid mixed prairie savanna. These semiarid grass-shrub savanna rangelands probably have a closer affinity structurally and floristically with arid semidesert grasslands that are in closer proximity to the Stockton Plateau and/or Chihuhuan Desert than they do with the tallgrass prairies, Cross Timbers, and post oak savannas to the east and north. Examples of this include many of the rangelands (range types) of the western Edwards Plateau as in much of Sutton, Edwards, and Kinny Counties, Texas. This rangeman felt that the brief and generic description of native range vegetation of the central and western Edwards Plateau by Riskind and Diamond in Amos and Gehlbach (1988, ps. 13-14) was much more accurate and realistic (even though abbreviated) than the rather elaborate site descrptions by the SCS/NRCS in regards to relative cover and dominance of tallgrasses on shallow soils in semiarid precipitation zones. Description of the general Edwards Plateau savanna range plant community in the Juniper-Oak (SRM 733) rangeland cover type (Shiflet, 1994) was also more realistic, but it did not distinguish between eastern subhumid (mesic) and western semiarid (xeric) portions of the "Hill Country". There is considerable variation in average precipitation in the east to west extent of range types (and even in range sites) across the Edwards Plateau. Climatic atlases and other references typically show four or five four-inch increment isohytes over the east to west expanse of the Edwards Plateau (eg. Bomar, 1983, ps. 55, 57). Dominant woody species on the range presented here was plateau live oak, but judicuous brush control permitted scattered individuals of Ashe and redberry juniper, honey mesquite, agarito, Texas persimmon, and whitebrush. Edwards County, Texas. October, autumnal aspect. FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna) and SRM 733 (Juniper-Oak).. Mixed Grass-Scrub Series 143.14 (Brown et al., 1998, p. 40). Low Stony Hills (East) range site. Semiarid Edwards Plateau Ecoregion, 30d (Griffith et al., 2004).

37. Composition and structure of semiarid live oak-mixed praire Edwards Plateau savanna- Two views at scale of range plant community showing architecture and species make-up of mixed prairie. There were distinctive vegetational layers of tall-, mid-, and short grass species with plateau live oak (the dominant woody plant) along with juniper and mesquite (associate woody species) that comprised a savanna in the semiarid section of Texas Edwards Plateau. Dominant species of the shortgrass layer were curly mesquite and buffalograss with hairy and red gramas being local associate shortgrasses. Major midgrass species included silver bluestem, plains lovegrass, sideoats grama, Texas cupgrass, and Texas wintergrass or Texas speargrass. Green sprangletop, represented by individuals exceeding a yard in height, was also a major--sometimes a local-- dominant species. Distinction between midgrass and tallgrass is often arbitrary for such species as green sprangletop and Texas cupgrass, both of which were common on this range and reached the same height at maturity as the associated little bluestem. Canada or nodding wildrye was locally abundant beneath live oats where this cool season grass was associated with Texas wintergrass. The dominant plant species on this range that is always designated as a tallgrass was little bluestem. Little bluestem was followed in general abundance by tall dropseed with Indiangrass an occasional species while Johnsongrass was present as incidental plants. Less common grasses or those having less relative cover included common windmillgrass and purple threeawn. The most abundant forbs were two native perennials: copper or narrowleaf globemallow and orange daisy or orange zexmenia. Western ragweed was locally abundant, sometimes forming small exclusive stands. These ragweed stands or colonies had developed on soil laid bare by mechanical brush control (see below) and were not typical of undisturbed range vegetation. Naturalized Mediterranean herbs included annual bromes ( seedlings present likely included both cheatgrass and Japanese chess) plus redstem filaree or strork's bill. These were infrequent, but it was early autumn and there may have been later germination/emergence of these annuals. Mechanical treatment (bulldozer) of individual plants resulted in reduction in density and cover of both redberry and blueberry juniper and honey mesquite along with associated Texas persimmon. Smaller plants and a few larger individuals of these species remained along with those of agarito, whitebrush, soapweed yucca, pricklypear, and tasajillo. Edwards County, Texas. October, autumnal aspect. Peak standing crop of warm season species and range vegetation overall. Phenology of grasses varied from grain-ripe to grain-shatter stages in sideoats grama, silver bluestem, green sprangletop, and plains lovegrass; soft to mid-dough stage in Texas cupgrass and little bluestem; greenup of Texas wintergrass; and early seedling stage in annual Eurasian species. FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna) and SRM 733 (Juniper-Oak).. Mixed Grass-Scrub Series 143.14 (Brown et al., 1998, p. 40). Low Stony Hills (East) range site. Semiarid Edwards Plateau Ecoregion, 30d (Griffith et al., 2004).

38. Samples of Edwards Plateau mixed prairie sward- Composition and structure of herbaceous layers of Edwards Plaeau live oak-mixed prairie savanna was portrayed in these two photographs. Two conspicuous herb layers were visible in both of these slides. Grasses readily discernable in the first photograph included plains lovegrass, silver bluestem, and Johnsongrass. The conspicous forb was western ragweed, an invader. This local microhabitat (= microsite) had been mechanically disturbed and plant species of the three successional statuses of decreaser, increaser, and invader were present in this one small photo-plot. Herbaceous range vegetation in the second slide was on an apparently undisturbed microenvironment. Major grasses included green sprangletop (which on this habitat achieved a mature height equal to that of little bluestem), sideoats grama, Texas cupgrass, and plains lovegrass. Hairy grama was the only common shortgrass species on this photo-quadrant. Therefore, this "plot" was predominantly a midgrass layer (stand of midgrasses). Such local stands of vegetation that were composed of most plants having similar heights were common. This general result was small-sized patches of various plant species arranged as "spots" of short-, mid-, and tallgrasses. Often range forbs were associated with grass species of similar or corresponding relative mature heights (eg. copper globemallow associated with plains lovegrass and green sprangletop). In this pattern, mixed paraire consisted of patches of range plant stands each of which tended to be dominated by either short-, mid, or tallgrass species rather than as a more uniform sward in which tall-, mid-, and shortgrasses were in almost all local groups of range plants. The herbaceous patchwork pattern was a more common arrangement. Diversity consisted of numerous patches differing in botantical make-up and not of a fairly uniform, diverse mix of plant species throughout the plant community (across the range). Edwards County, Texas. October, autumnal aspect. FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna) and SRM 733 (Juniper-Oak).. Mixed Grass-Scrub Series 143.14 (Brown et al., 1998, p. 40). Low Stony Hills (East) range site. Semiarid Edwards Plateau Ecoregion, 30d (Griffith et al., 2004).

39. Some more samples of Edwards Plateau mixed prairie sward- Diversity in range compostion of herbaceous plants was presented in two photo-quadrants on semiarid mixed prairie an Excellent range condition class. These samples of range vegetation were on the same range as featured in the preceding six (two sets of three) slides. Obvious species present in this range plant community as shown in the first slide included green sprangletop, Texas wintergrass (large bunchgrass behind and slightly to left of prominent green sprangletop), sideoats grama, common windmillgrass (far-right, rear margin), and copper globemallow (the conspicuous forb) in background. In the second slide copper or narrowleaf globemallow opverwhelmed the stage while sideoats grama followed by green sprangletop played graminaceous escort. A "rogue" leaf of alien Johnsongrass in left foreground served as a size reference for leaves of copper globemallow. Edwards County, Texas. October, autumnal aspect. FRES No. 32 (Texas Savanna Ecosystem). K-77 (Juniper-Oak Savanna) and SRM 733 (Juniper-Oak).. Mixed Grass-Scrub Series 143.14 (Brown et al., 1998, p. 40). Range site: Low Stony Hills (East). Semiarid Edwards Plateau Ecoregion, 30d (Griffith et al., 2004).

40. Plains lovegrass (Eragrostis intermedia)- Hearty specimens of a dominant climax (decreaser) grass on the semiarid Texas Edwards Plateau mixed prairie-shrub savanna. Like the more common and, often, associated sideoats grama, the successional status of plains lovegrass varies widely depending on range type and range site. On harsher habitats such as in the semiarid zone, on shallow soils, and south or west slopes of the Edwards Plateau plains lovegrass is a decreaser. On more mesic range sites in the eastern Edwards Plateau this species responds more like an increaser. Plains lovegrass is often a major forage producer that yields comparatively large quantities of palatable, nutritious herbage. It has been widely used in reseeding former cropland in the Great Plains, especially as a component of species mixtures for land in the Conservative Reserve Program. This bunchgrass typically has considerable capacity for asexual reproduction via tillering. Plains lovegrass is also a good producer of viable grain so that this widespread native grass also reproduces sexually. Given its palatablity, potential for high yield under semiaridity, successional status, ease of establishment, and geographic range plains lovegrass is usually regarded as the single most important Eragrostis species on North American ranges. These plants were on the same Edwards Plateau live oak-mixed prairie savanna range as presented in the immediately preceding four sets of photographs. Edwards County, Texas. October, seed-ripe stage.

41. Pains lovegrass from closer views-Many of the Eragrostis species have a general shoot morphology consisting of a basal tuft of leaves from which arise proportionally long culms that terminate in some of the longest panicles of any grasses of comparable size. The first of these two slides presented an individual of plains lovegrass displaying the disproportionately lengthy and generally large panicle of this species. The second of these slides presented the typical tuft of leaves at base of this same plains lovegrass plant. This individual was growing on the near-climax Edwards Plateau live oak-mixed prairie range that was featured immediately above. Edwards County, Texas. October, peak standing crop at seed-ripe stage.

42. Inflorescence of plains lovegrass- Detailed views of the upper culm and panicle of plains lovegrass presented to shown key characteristic of this major species of Edwards Plateau ranges. The first photograph showed flag leaf subtending the panicle and base of panicle and rachis. One of the most distinguishable key identifying features of plains lovegrass is the numerous tufts of pilose or silky hairs in some upper leaf axils and and at points along the panicle rachis. This characteristic was presented in this slide. Second photograph showed the much-branched panicle with a characteristic sparse number of spikelets. This was the same individual plant featured in the immediately preceding set of two photographs. Edwards County, Texas. October, grain-ripe phenological stage.

43. Part of a panicle of plains lovegrass- Photograph showing a section of the spreading panicle of plains lovegrass revealing the potential of this species to "set seed" when growing--especially soil moisture--conditions are favorable. Edwards County, Texas. October, hard-dough to grain-ripe stage.

44. Spikelets of plains lovegrass- Portion of panicle of the plains lovegrass plant shown in preceding slides presenting the arrangement of spikelets which are fewer-flowered (generally 3 to 8 or 10 florets per spikelet) than many, probably most, Eragrostis species. Edwards County, Texas. October, grain-ripe stage of phenological development.

45. Closer look at plains lovegrass spikelets- Several spikelets of plains lovegrass were shown for greater detail and clarity of these fundamental units of the grass inflorescence. Lovegrasses (Eragrostis spp.) have some of the smallest grains and spikelets among the North American Gramineae. Edwards County, Texas. October, hard-dough to grain-ripe stage.

46. Texas cupgrass (Eriochloa serecia)- Large individual of Texas cupgrass growing among Texas wintergrass, sideoats grama, and green sprangletop on the near-climax Edwards Plateau live oak-mixed prairie savanna range introduced above. Texas cupgrass is an extremely palatable, native panicoid grass that is rapidly grazed out under excessive stocking, especially of cattle or horses. This species is generally interpreted as a decreaser though, of course, disturbance responses are range site-specific. On various range sites in the Edwards Plateau as well as adjoining portions of the Rio Grand Plains Texas cupgrass is typically associated with green sprangletop, plains lovegrass, sideoats grama, and Texas wintergrass. Texas cupgrass is a densely tufted bunchgrass with asexual reproduction limited to tillering.. This individual exceeded two and a half feet in height and was growing beneath the crown of a plateau live oak. Photographs of panicles of this particular plant were presented immediately below. Edwards County, Texas. October, soft to mid-dough stage of phenology. Low Stony Hills (East) range site.

47. Inflorescence of Texas cupgrass- Set of three photographs to show the arrangement and details of spikelets in the contracted panicle of this panicoid grass. In this species, spikelets are arranged along unbranched primary branches that lie closely --almost adnate--to the central axis of the panicle (Gould, 1975, p. 433). Hitchcock and Chase (1950, p. 588-589) interpreted the inflorescence of Texas cupgrass as consisting of racemes along a rachis. The interpretation by Gould (1975, p. 433) was consistent with recognition of six subfamilies of Gramineae and more phylogentically precise than the more artificial approach of only two broad subfamilies used by Hitchcock and Chase (1950). The unique floral feature of this species is the small indentation or depressed portion of the branch in which the caryopsis is situated, hence the common name of cupgrass (ie. depression in which the grain lies is a "cup"). Inflorescences on the individual specimen shown immediately above. Edwards County, Texas. October, soft to-mid dough phenological stage.

48. Green sprangletop (Leptochloa dubia)- Large single plant of green sprangletop with several sexual (floral) culms plus several inflorescences (right foreground) of a second plant that was "off-stage". On shallow, rocky range sites in semiarid parts of the Edwards Plateau green sprangletop is usually regarded as a decreaser as it typically declines rather quickly on such harsh sites with heavy grazing (and, of course, overgrazing). Green sprangletop grows in association with sideoats grama, Texas cupgrass, Texas wintergrass, and silver bluestem or pinhole bluestem on mixed prairie savanna rangeland in the semiarid Edwards Plateau. Green sprangletop can grow to mature heights exceeding three feet. The individual shown in this photograph reached two and a half feet and thus was an example of the habit and size of the larger form of this species. Other individuals of green sprangletop are considerably shorter and smaller overall, especially under heavier grazing. This example was growing on the Excellent condition Edwards Plateau live oak-mixed prairie savanna range described above. On many range sites, including some sites of semidesert grassland, green sprangletop is regarded as an increaser. On various of the shallower, more xeric range sites in the semiarid Edwards Plateau green sprangletop has a response more like that of a decreaser. Gould (1975, p. 226) described this eragrostoid grass as being strictly cespitose with neither stolons nor rhizomes, buth Hatch and Pluhar, 1993, p.99) ascribed rhizomes to green sprangletop and Silveus (1933, p. 368) implied the same. Edwards County, Texas. October, immediate post-peak standing crop at grain-shatter phenological stage.

49. Inflorescence of green sprangletop- An inflorescence on the large individual green sprangletop featured in the preceding photograph. The common name of sprangletop refers to the spreading--hence, "sprangled"--arrangement of the inflorescence. Generically speaking the inflorescence of this member of the Eragrostoideae subfamily consist of numerous racemes on primary branches directly off of the rachis. Edwards County, Texas. October, grain-ripe to grain-shatter stage.

50. Young flowering shoots and inflorescences of green sprangletop- Late summer shoots of green sprangletop that developed following soaking rains after a severe summer drought These late-season shoots were either stunted (or would appear as such) because there was not enough growing season remaining to permit development to normal mature size of sexually reproductive shoots in this species. Photoperiod was certainly a major factor in this regard, though the phenomena of photoperiod interacted with drought stress. Green sprangletop produces cleistogomous spikelets enveloped within sheaths of basal leaves (ie. in effect, still in the boot). Cleistogamy is the condition in which flowers do not open normally so that any fruit produced is through self-pollination and self-fertilization. Cleistogamy existed in green sprangletop shoots shown in both of these two photographs. A clone, clonal unit, or ramet of one (the same) green sprangletop plant was shown in each of these slides. On each clone there were very short shoots that remained encased within a folded sheath and unopened blade of a single leaf (ie. the boot). These were present at the base and in front of the more obvious stunted shoot that was bearing an emergent inflorescence. Within the boots of these extremely short shoots there were "hidden"-- meaning unexerted-- inflorescences. Again, these shortest shoots were in front of both stunted shoots that bore newly emergening or exerted inflorescences (one shoot with an opening inflorescence in each of these slides). These "hidden" inflorescences were retained within the boot and these unopened racemes were bearing cleistogomous spikelets. The tips of these cryptic inflorescences were barely visible (appearing as pubescence) from tip of the boot (= folded leaf). Erath County, Texas. Understorey of Western Cross Timbers. September. Again, two forms of the flowering stage of phenological development: 1) inflorescence emerging from the boot and 2) nonemergent or unexerted inflorescence (retained within the boot) bearing cleistogamous flowers.

51. Anthesis in green sprangletop- The distal portion of a green sprangletop inflorescence, the racemes--with young florets and their exerted anthers--of which were spreading or extending away from the rachis. This stage of floral development was a day or two advanced beyond emergence of the inflorescence from the boots on separate shoots as presented in the two slides immediately above. Erath County, Texas. Understorey of Western Cross Timbers. September, anthesis.

52. Champi