Preliminary Report of an Ethnobotanical Survey along the Ogallala Ecotone on the Dempsey Divide

Roger Mills County, Oklahoma

J. Peter Thurmond, Dempsey Divide Research Foundation, Inc.; Oklahoma Anthropological Society, Inc.;

Sam Noble Oklahoma Museum of Natural History, University of Oklahoma;

Thurmond Ranch, Inc.; Western Oklahoma Financial Services, Inc.

Craig C. Freeman, Kansas Biological Survey, Kansas Natural Heritage Inventory, R.L. McGregor Herbarium, University of Kansas Natural History Museum and Biodiversity Center, University of Kansas.

Kelly Kindscher, Department of Ecology and Evolutionary Biology, Environmental Studies Program,

Kansas Biological Survey, Kansas Natural Heritage Inventory, University of Kansas.

Hillary Loring, Kansas Biological Survey, University of Kansas.

Caleb A. Morse, R.L. McGregor Herbarium,

University of Kansas Natural History Museum and Biodiversity Center, University of Kansas.

Bruce W. Hoagland, Department of Geography, Oklahoma Biological Survey,

Oklahoma Natural Heritage Inventory, University of Oklahoma.

Introduction

An intensive botanical survey of the 9275 acre (3755 ha) Thurmond Ranch in southern Roger Mills County, Oklahoma was performed in the spring, summer, and early fall of 2001. Field work was conducted by personnel of the Kansas Biological Survey and the R.L. McGregor Herbarium of the University of Kansas, and the Oklahoma Biological Survey of the University of Oklahoma. The purpose of the project was to document and collect the floral species growing along the Ogallala ecotone, as an adjunct to ongoing, long-term archeological and paleoclimatological research in the Dempsey Divide study area (Bement 2000; Bement and Buehler 1994, 1998; Buehler 1997; Thurmond 1990, 1991a, 1991b, 1991c, 1997; Thurmond and Picarella 1999; Thurmond, Wyckoff, and Batchelor, 1998; Thurmond and Wyckoff 1998, 1999, 2001).

The place name "Dempsey Divide" was coined by Thurmond (1990) for the uplands between the Washita and North Fork of the Red rivers in western Oklahoma. The other major interfluvial divides of northwestern Oklahoma have been subsequently named (Thurmond and Wyckoff 1999). Lead botanists on the botanical survey were Craig Freeman, an authority on Great Plains plant systematics and taxonomy (c.f. Collins et al. 1995; Freeman 1998a, 1998b, 2002; Freeman and Schofield 1991; Freeman et al. 1997, 1998); and Kelly Kindscher and Hillary Loring, specialists in Great Plains ecology and ethnobotany (Kindscher 1987, 1992, 1995; Kindscher et al. 1996, 1998; Lauver et al. 1999; Loring et al. 1999, 2000). As a result of this survey, the Thurmond Ranch was listed on The Oklahoma State Register of Natural Heritage Areas, administered by the Oklahoma Biological Survey, in September of 2001 (Shannon 2001, 2002).

The Dempsey Divide Study Area and the Thurmond Ranch:

An Intersection of Geology, Climate, and People

The bulk of the archeological and paleoclimatological research on the Dempsey Divide has been conducted on the Thurmond Ranch (hereafter referred to simply as "the ranch"), a fourteen square mile (36 km²) contiguous block to the immediate southwest of the town of Cheyenne, in southern Roger Mills County, Oklahoma. The ranch is on the north side of the Dempsey Divide, and extends from its crest to the edge of the modern valley of the Washita River. It is drained by three short, spring-fed, steep-gradient tributaries of the Washita: Brokenleg, Plum, and Sergeant Major creeks. These streams drop some 400' (120 m) in their 7 mile (11.3 km) descent across the ranch to the Washita. The north-flowing tributaries of this river have incised a dense dendritic drainage network on the north side of the divide, creating canyon systems characterized by arroyo cut and fill cycles (c.f. Schumm and Hadley 1957) operating on centennial and millennial time scales. The most recent arroyo incision cycle began around the turn of the 20^th century, triggered by the intense land use of the early post-1892 white settlement (homesteader) period.

Air photo analysis indicates that approximately 1560 ac (630 ha, or 16.8%) of the ranch was farmed, and most of the rest was intensely grazed in the 1890s and early 1900s. A family lived on and subsistence farmed virtually every quarter section during this time, inflicting an intense insult upon the land. The homesteaders began to leave around 1915. Most of the land comprising the ranch was purchased by the first author's family between 1915 and 1945. The last of the cultivated land was put back to grass in the early 1960s, and land use has been limited to low-intensity grazing by cattle, horses, and llamas since that time. The deer (Odocoileus virginiana) and turkey (Meleagris gallopavo) populations on the ranch have been growing rapidly since the 1980s. Some limited disturbance by deep drilling for natural gas has occurred since the late 1970s. Erosion on the ranch has been brought under control by the recovery of the vegetation and the construction of some 562 erosion control structures in cooperation with the USDA Natural Resources Conservation Service under their Critical Area Treatment (CAT) program.

The ranch straddles a major geological and ecological boundary, the eastern outcrop edge of the Tertiary Ogallala Formation. The Ogallala is outwash from the front range of the Rocky Mountains, deposited across much of the western Great Plains in Late Miocene to earliest Pliocene times by interior continental (dryland) anastomosing streams that have no modern analogue. Vertebrate local faunas of the Ogallala Formation on the Southern Plains are of Clarendonian to Hemphillian age, dating from 12 million to 4.5 million years ago (Czaplewski et al. 2001). Western Oklahoma was arid grassland at the time of Ogallala deposition, but the streams flowing though the area headed up in the Rockies. Intense rainfall in the mountains resulted in periodic fluvial transport of coarse sediment out onto the plains, where it was dumped as each flood ran out of steam (Frye and Leonard 1957; Gustavson and Finley 1985; Gutentag et al. 1984; Reeves and Reeves 1996; Ryder 1996; Seni 1980). Cobbles as large as 40 cm in maximum dimension can be seen in the basal Ogallala Formation on the ranch. Much of the sediment comprising the lower part of the Ogallala is quite sandy, and the formation is a major aquifer (Reeves and Reeves 1996).

The Ogallala was deposited on an eroded Miocene prairie landscape with a mature dendritic stream network, not unlike the modern one, developed on redbeds of Late Permian age (Gustavson and Finley 1985; Gustavson and Winkler 1988). The geologic unit directly underlying the Ogallala locally is the Doxey Shale, and it is in turn underlain by the Cloud Chief Formation (Bowers 1967, Carr and Bergman 1976). These three units are all quite different from one another, with profound effects on the topography, vegetation, and history of human use.

The generally pale brown to white, sandy lower Ogallala forms a gently rolling landscape atop the Dempsey Divide, and was significantly reworked by the wind into dunes and deflation basins in Late Pleistocene times (Thurmond and Wyckoff 1998). Given its predominantly fluvial origin, the texture and degree of cementation of the Ogallala are quite variable over short distances. Scattered thin calcareous sandstones are present which formed in broad, shallow lakes that periodically dried up. A "red Ogallala" facies occurs in the lower part of the formation, of variant expression from place to place, that represents Miocene reworking of Permian clastics at the inception of Ogallala deposition (Czaplewski et al. 2001; Neil H. Suneson, Oklahoma Geological Survey, personal communication, 2001). Deposition of the Ogallala Formation ceased in Pliocene times, and its eastern edge has been eroding back to the west through most of the Pleistocene. This retreat is apparently episodic, effected through cycles of cut and fill, but episodes of retreat can be quite rapid. The Ogallala outcrop edge on the Thurmond Ranch retreated by over a mile at the end of the last glaciation, between 15,000 and 10,000 years ago (Thurmond and Wyckoff 2001).

The Doxey Shale is a dark red series of discontinuous claystone and sandy siltstone laminae. The Doxey formed in a coastal floodplain environment, under a tropical, monsoonal climate much like that of southern India today. Oklahoma was in fact a part of the Pangaean supercontinent at that time, and located just south of the equator (Pan Terra, Inc. 1994). The Doxey is comprised principally of ancient thick, buried vertisols, which slowly accumulated on the coastal floodplains as a product of low-energy overbank flooding. Pedogenesis destroyed all sedimentary structure, and slickensides are still visible on the angular blocky ped surfaces. These now indurated soils are punctuated by crevasse splay sandy siltstones, each formed in no more than a few days, as a result of levee breaching during exceptionally violent riverine floods (Suneson op cit.).

The Doxey is quite dense and fine-textured on average, and resists downward percolation of groundwater. As a result, many of the streams leading off the Ogallala are spring-fed where the modern drainages cross the outcrop edge. The location and strength of the modern springs is controlled in part by the buried landscape under the Ogallala; groundwater follows the topographic lows formed by Middle Miocene paleovalleys. Minor seeps and springs can be found out in the Doxey outcrop in wet years, where groundwater pipes through joints in the formation under hydraulic head from local Ogallala recharge (Thurmond et al. 1998). Given its texture, the Doxey is fairly resistant to erosion, and is typified by deep canyonlands in the upper part of its outcrop. Isolated remnants just beyond the Doxey outcrop edge form characteristic conical "haystack" hills (Bowers 1967).

The underlying Cloud Chief Formation is a pastel red mix of soft, finely laminated silty sandstone, punctuated by thin beds of gypsum. The Cloud Chief was deposited primarily in marine littoral and shallow near-shore environments. It erodes much more evenly and readily than the Doxey Shale, and is characterized by gentle, rolling topography. Stream valleys open out, and stream and slope gradients drop dramatically when you pass from the Doxey outcrop to that of the Cloud Chief. Evaporites in the Cloud Chief had a profound post-depositional effect on the overlying Doxey Shale, probably during the time when both were buried under the Ogallala aquifer (Caran and Baumgardner 1990, Martinez et al. 1998). Dissolution of the deep Cloud Chief has resulted in discontinuous but significant subsidence of the Doxey. The latter is often tilted, fractured, and weakly faulted. None of this deformation is of tectonic origin. Bizarre karst landforms and stream diversions are aerially visible in the Doxey outcrop.

Given the complex geology and often intensely dissected terrain, the soils along the north side of the Dempsey Divide are a highly variable patchwork. Soils on the Ogallala outcrop tend to be calcareous, but on average are deep, sandy mollisols. The coarse texture, in combination with a gentle, often internally drained relief atop the Ogallala outcrop, results in much higher effective precipitation than on the Permian outcrops, especially the Doxey Shale. The latter formation is characterized by extensive exposures of weathering bedrock and orthents, except where Late Holocene gully fills have facilitated the development of isolated alfisols, inceptisols, and shallow mollisols. The more gentle landscape and moderately coarser texture of the Cloud Chief outcrop is associated with more extensive areas of the latter soil types, but evaporites often discourage plant growth in eroded areas.

Let us emphasize that the fundamental contrast within the study area is between the Ogallala outcrop and the underlying/adjacent Permian redbeds. Because the terrain and soil texture on the Ogallala combine to yield significantly higher effective precipitation, due to much higher infiltration, that outcrop is associated with a much higher vegetal biomass and apparent biodiversity than the adjacent Permian outcrops. This fact has long been observed by the archeologists working on the Dempsey Divide, and was the impetus of the current botanical survey. A remarkable concentration of prehistoric hunter-gatherer campsites is associated with the ecotone formed by the Ogallala outcrop edge, and it has been inferred that these sites were situated to make most efficient use of the varying floral and faunal communities found on either side of this boundary (Thurmond 1990, 1991b).

However, human use of the Ogallala ecotone on the Dempsey Divide was not continuous over time, and this discontinuity appears to be a function of climate change. Most human habitation occurred during the first Christian millennium, with lesser peaks during the Early Holocene (10,000-8000 rcy BP) and Protohistoric (AD 1450-1700) periods (op cit.). Regional climate was extremely unstable, but on average cooler and wetter in Late Pleistocene to Early Holocene times. The upland valleys of the ranch were choked with marshy sediment at this time (Thurmond and Wyckoff 2001). Climate deteriorated rapidly around 7,000 years ago into the Altithermal, a drought which lasted for millennia, and the region turned to desert (c.f. Antevs 1955; Holliday 1989; Meltzer and Collins 1987; Reeves 1973; Toomey et al. 1993). The study area was virtually uninhabited during most of the Middle Holocene (Thurmond and Wyckoff 1999).

The canyons of the ranch incised their fills during the Altithermal, and apparently remained open until its end. Increasing rainfall around 3,200 years ago initiated rapid refilling of the canyon system with sediment, and people returned to the area late in the first millennium BC. On average, climate during the first millennium of the Christian era was the wettest of any time since the Early Holocene, and the most recent millennium was much like today (Hall 1982, 1988, 1990). However, study of buried soils on the Dempsey Divide by Thurmond and Wyckoff (2001) has revealed a century-scale cycle in rainfall, operating since late glacial times, that is particularly well documented for the last two millennia. Regional climate oscillates between wetter (pluvial) and drier (interpluvial) conditions and back again roughly every four hundred years. Since 50 BC, the pluvials have averaged 185 years in duration, and the interpluvials 205 years. Late Holocene pluvial duration has varied from 150 to 225 years on the Southern Plains (ibid.). We are currently in the pluvial half of the cycle, and average annual rainfall has increased by some 25% over the past century. Analysis of 20^th century rainfall on the Dempsey Divide reveals a roughly 20 year cycle as well (ibid.). The most recent peak in this decadal cycle was in the late 1990s (Thurmond and Thurmond 2001).

In its geology, geomorphology, and climate (and the three are obviously interrelated), the eastern outcrop edge of the Ogallala Formation is a very unstable and dynamic area. The local vegetation must surely be adapted to this inherent character.

The 2001 Ethnobotanical Survey

Floral species were collected and documented by the University of Kansas and University of Oklahoma personnel in the summer of 2001 by geologic outcrop and topographic/geomorphic setting. Each species was vouchered in the collections of both the R.L. McGregor Herbarium, University of Kansas, and the Robert Bebb Herbarium, University of Oklahoma. Three permanent sampling plots were established on each of the three principal geologic outcrops. Digital floral distribution maps in GIS format are in preparation. A current and complete list of the flora of the Dempsey Divide study area is posted on the Internet at http://www.geocities.com/dempseydiv/, and will be updated periodically. A detailed botanical reporting of the vouchered flora from this survey is in preparation, detailing floral associations by geologic outcrop and habitat, and summarizing the vegetation alliances of the study area (Freeman et al. n.d.). Kindscher and Loring plan a more detailed report of the ethnobotany of the Dempsey Divide.

The results of the 2001 botanical survey fulfill and exceed all prior expectations. A surprising diversity of floral taxa survived the profound environmental insults of the Altithermal and the homesteaders. We say taxa, rather than species, because multiple subspecies and/or varieties have been documented for some floral species. A first-pass reconnaissance of the ranch in the summer of 2000 by Kindscher and Loring identified 168 taxa. Monthly collecting forays were made by the authors (principally Freeman, Loring, and Morse) during the 2001 growing season, from April to October. By July of 2001, the taxonomic count had risen to 334. As of 01/31/2002, our current floral taxa count is 490. Continued monitoring is planned in coming years to identify plant taxa that have been missed. This botanical survey of the Thurmond Ranch was performed at a time when the local vegetation had been stressed by a string of hot, dry summers. Based on the experience of the Kansas Biological Survey personnel with long-term botanical monitoring at the Tall Grass Prairie Preserve in Osage County, Oklahoma, a significant number of additional plant taxa is expected to be documented along the Ogallala ecotone on the Dempsey Divide in future, wetter years (c.f. Loring et al. 1999).

Of the taxa collected to date, 44 (9.0%) are (mostly inadvertent) introductions from Eurasia. Another four species are native to North America, but probably represent deliberate post-1892 homesteader introductions: Campsis radicans (trumpet vine), Carya illinoinensis (pecan), Catalpa speciosa (catalpa), and Maclura pomifera (bois d'arc). Trumpet vine is observed only in very protected settings adjacent to old homestead sites on the Dempsey Divide (only near the long-occupied Sarah Clines homestead on the ranch, at Brokenleg Springs). Pecan is found only at one homestead site adjacent to the ranch, on the lower reaches of Brokenleg Creek. However, Marcy noted pecan on the North Fork of the Red River as far west as the Texas line in 1859 (Foreman 1937). If pecan is locally introduced, it was perhaps not carried very far. Catalpa is known to have been transplanted by settlers, and was sometimes used in shelterbelt plantings. Its distribution along the spring-fed creeks in Roger Mills County is spotty, suggesting a fairly recent origin. Bois d'arc is found only in or near planted shelterbelts. Schambach (2000) believes the prehistoric Late Holocene range of bois d'arc was limited to a small area south of the Red River in northeast Texas, adjacent to the Sanders archeological site.

Echinochloa muricata v muricata (barnyard grass) and Juglans nigra (black walnut) could represent deliberate prehistoric introductions. Echinochloa was recovered from a Late Woodland (ca. AD 900-1000) context just below Brokenleg Springs, in the 1988-1991 Oklahoma Anthropological Society excavations at 34RM208A, the Beaver Dam site (Richard R. Drass, Oklahoma Archeological Survey, personal communication, 2001). Black walnut is fairly ubiquitous along the creeks and upland draws. These could be relict stands from the Early Holocene, but black walnut was a favored Native American nut tree, and far superior to the clearly indigenous Juglans microcarpa. The third author thinks it likely that indigenous peoples carried and transplanted J. nigra nuts into favorable habitats outside its then-current range prior to the 1890s. However, given our uncertainty as to the origins of these two species on the Dempsey Divide, we treat them herein as species native to the study area.

One of the clearly introduced Eurasian species, Acorus calamus (sweetflag), merits discussion. There was initial excitement when a patch of sweetflag was found growing at Brokenleg Springs. There are only two prior records of sweetflag in Oklahoma, in Cleveland and Stephens counties. Sweetflag is often found growing in marshes adjacent to Plains Village sites in the Central and Northern Plains, where it is interpreted as a Native American transplant (Gilmore 1931:90). However, there is a tremendous amount of confusion in the literature concerning the genus Acorus in North America. In most of the literature the name Acorus calamus has been applied to all populations of North American plants. But recent analysis of sweetflag morphology, essential oil chemistry, isozomes, and cytology have resulted in a subdivision into two species: A. calamus, an introduced (Eurasian) sterile triploid; and A. americanus, a fertile diploid, which is native to North America (Thompson 2000). The latter is distributed primarily across the northeastern and midwestern United States and southern Canada.  Thompson (ibid.) shows the distribution of A. calamus throughout much of the eastern United States, with scattered occurrences on the Great Plains, based on herbarium material she borrowed and verified. The closest documented occurrence of A. americanus is in northeastern Nebraska.  The two species are distinguished most easily on the basis of vegetative features, since A. calamus produces flowers, but never has mature fruits. The leaves of the specimens from the ranch have a very prominent midvein, with much less prominent lateral veins - characteristic of the Eurasian sweetflag.

The Brokenleg Springs sweetflag patch is adjacent to the Sarah Clines homestead, and could conceivably have been planted by her in the early 20^th century. However, white settlers did not make much use of this plant. We believe an earlier Native American introduction of the species to the Ogallala ecotone is likely, given the strong (and continuing) ethnobotanical importance of sweetflag to Native Americans (c.f. Cheatham et al. 1995; Motley 1994), the timing of its advent in North America, and the local archeological record. Mabry (1977:141) reports that A. calamus arrived in North America from Europe in 1567. The third author believes it likely that the sweetflag Gilmore (op cit.) reports transplanted by the Pawnee and other tribes was A. calamus, not A. americana, based on the locations involved. And although AD 1000-1450 Plains Village sites are rare on the Dempsey Divide (Thurmond and Picarella 1999), post-AD 1450 Protohistoric sites are not uncommon (Thurmond 1991b). The first author has observed A. calamus growing in the Ogallala ecotone along Trail Branch Creek on the Durham Divide, in northern Roger Mills County. We think it likely that sweetflag is fairly common in marshes and on perennial streams along the Ogallala ecotone on the Dempsey Divide. The distribution and origin of sweetflag on the Southern Plains is a topic worthy of further study.

So 442 taxa, or 90.0% of the total collected, appear to be native to the study area. Of these 442 taxa, 19 (4.3%) are identified as disjunct; i.e. present as isolated occurrences more than 100 km from the area of common occurrence of each taxon. Another 27 taxa (6.1%) are considered edge-of-range, or at the margin of their modern range. A listing of the identified disjunct and edge-of-range floral taxa is provided in Tables 1 and 2. The modern range data derive from Atlas of the Flora of the Great Plains (Great Plains Flora Association 1977), The PLANTS Database, Version 3.1 (USDA Natural Resources Conservation Service 2001), Catalog of the Woody Plants of Oklahoma (Johnson and Hoagland 2001), and the collections of the Robert Bebb Herbarium, University of Oklahoma (Wayne Elisens, Robert Bebb Herbarium, personal communication, 2002).

Ethnographically known useful plants are indicated with a superscript "u" in Tables 1 and 2. Fourteen of the 19 disjunct taxa (73.7%), and 15 of the 27 edge-of-range taxa (55.5%), are known useful plants. For the disjunct taxa, that percentage rises to 89.5% if the two threeawns, possible inadvertent 20^th century agricultural introductions, are excluded. The remaining disjuncts and most of the other edge-of-range taxa have close relatives that are known to have been used as medicinal plants. It is possible that nearly all of the disjunct and edge-of-range taxa were useful plants. Most of these plants would have been unavailable to groups living further to the west. Medicinal plants may have represented valuable and readily portable items of trade for the native inhabitants of the Canadian, North Fork, and upper Washita basins, particularly in Late Prehistoric and Protohistoric times. There are Late Prehistoric village sites within walking distance of the basal Ogallala springs along the Washita River (files of the Oklahoma Archeological Survey, 2001). Plant collecting forays into the uplands of the Dempsey Divide from these villages would have left little, if any, lasting archeological record.

The known (generalized) uses of these plants can be found in Table 3. For more detailed information on how specific plants were used, pending publication of the final report of this ethnobotanical survey, the best basic references are Kindscher 1987, 1992; Moerman 1986, and Tull 1999. Non-botanists be forewarned that floral taxonomy is in a state of rapid flux at the start of the 21^st century. We use herein the current plant nomenclature as of this writing (Freeman 2002). Many of these scientific names are not the same as those one will find in the preexisting literature. As a convenience to the reader, a list of taxonomic synonyms, using Flora of the Great Plains (Great Plains Flora Association 1991) as the prior standard, is provided in Table 5.

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Table 1: Disjunct Floral Taxa of the Ogallala Ecotone

on the Dempsey Divide

100 Km+ beyond the Modern Core Range

1) Agalinis aspera, tall false foxglove. Range: primarily the Central and Northern Plains, but extending sporadically into Oklahoma. There is a cluster of records in five central Oklahoma counties, and an isolated record in Woods County.

2) Aristida basiramea, forktip threeawn. Range: the eastern half of the Central and Southern Plains, the Upper Midwest, and parts of New England and the Southeast. Not previously recorded in Oklahoma west of Canadian County.

3) Aristida purpurascens v purpurascens, arrow feather threeawn. Range: much of the eastern United States and parts of southeastern Canada. Interstate 35 marks the western edge of its distribution in Oklahoma, but for this record and a prior one in Jackson County.

4) Aster patens v patentissimus, sky drop aster. Range: the eastern half of Oklahoma, Arkansas, extreme southeast Kansas, and the southern two-thirds of Missouri. Again, all prior records for the species are east of I-35, but for one in Comanche County.

5) Botrychium virginianum^u, rattlesnake fern. Range: eastern margin of the Central and Northern Plains. Most common in the eastern third of Kansas and in Missouri. There are a few scattered records of this species in eastern Oklahoma, and an isolated one in Woods County.

6) Carex austrina^u, southern sedge. Range: eastern margin of the Central and Southern Plains. Most common in the eastern half of Kansas and western third of Missouri. Fairly common in the eastern half of Oklahoma, ranging west to Caddo and Comanche counties. There is an isolated record in Cimarron County.

7) Carex bulbostylis^u, eastern narrowleaf sedge. Range: the eastern half of the United States and southeastern Canada. The species is fairly common in the eastern two-thirds of Oklahoma, but isolated populations in Roger Mills County marshes are the only occurrence known west of Caddo County.

8) Cyperus acuminatus^u, tapeleaf flatsedge. Range: much of the eastern half of the United States. There are scattered occurrences in the eastern half of Oklahoma, but the species is regionally most common in the eastern three-quarters of Kansas, eastern half of Nebraska, and western half of Missouri. The westernmost prior records in Oklahoma are in Grant, Jefferson, and Kingfisher counties.

9) Cyperus lupulinus s lupulinus^u, Houghton flatsedge. Range: most of the northeastern quarter of the United States. Fairly common in central Kansas, but not previously documented in Oklahoma except for another isolated occurrence in Cimarron County.

10) Echinochloa muricata v muricata^u, barnyard grass. Range: much of the eastern half of the United States and southeastern Canada. The species is scattered across the eastern half of Oklahoma, but the closest concentration in its distribution is in the eastern half of Kansas and the western quarter of Missouri. The closest prior records in Oklahoma are in Alfalfa, Canadian, and Comanche counties.

11) Epilobium leptophyllum^u, bog willowherb. Range: much of the northern United States and southern Canada. Scattered occurrences have been documented in (mostly northern) Kansas, but this is the first record for Oklahoma.

12) Lechea tenuifolia^u, narrowleaf pinweed. Range: most of the eastern half of the United States. Most common regionally in the southeastern half of Oklahoma, western half of Missouri, and southeastern quarter of Kansas. The closest prior records in Oklahoma are in Canadian, Comanche, and Grady counties.

13) Polygonum tenue^u, pleatleaf knotweed. Range: most of the eastern United States and southeastern Canada. The species is regionally most common in eastern Kansas and western Missouri; it is also fairly common in eastern Oklahoma. The most westerly previous record in Oklahoma is in Comanche County.

14) Potentilla paradoxa, bushy cinquefoil. Range: much of the northern United States and southern Canada. The species is fairly common on the Northern Plains. A few scattered populations have been documented in western Kansas, eastern Colorado, and the northern Texas Panhandle. The only prior record for Oklahoma is in Woods County.

15) Pseudognaphalium obtusifolium^u, fragrant everlasting. Range: the eastern half of the United States and southeastern Canada. The species is fairly common in the eastern half of Oklahoma, but has not previously been documented west of Blaine and Canadian counties.

16) Rudbeckia subtomentosa^u, sweet coneflower. Range: the southern half of Iowa, western half of Missouri, extreme eastern Kansas; with scattered occurrences in the eastern quarter of Oklahoma and northwestern quarter of Arkansas. The closest prior record is in Bryan County in far southeastern Oklahoma.

17) Sporobolus clandestinus^u, southeastern rough dropseed. Range: most of the eastern United States, excluding Michigan and northern New England. The species is scattered across Oklahoma east of Interstate 35. The only prior record west of I-35 in Oklahoma is in Major County.

18) Stylosanthes biflora^u, sidebeak pencilflower. Range: the southeastern United States, including the Ohio River and southern Mississippi River drainage basins. Not previously recorded in Oklahoma west of Caddo and Grady counties.

19) Tragia betonicifolia^u, betony noseburn. Range: the southeastern third of Kansas, southwestern fifth of Missouri, and the north-central to northeastern quarter of Oklahoma. Not previously recorded in Oklahoma west of Garfield and Grady counties.

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Table 2: Edge-of-Range Floral Taxa of the Ogallala Ecotone

on the Dempsey Divide

Within 100 km of the Modern Core Range

1) Asclepias viridis^u, spider milkweed, green antelopehorn. Range: centered on the Mississippi River valley. The species occurs in the eastern half of the Central and Southern Plains, from southeastern Nebraska to Texas. It is common in the eastern three quarters of Oklahoma, but has not previously been documented west of Custer County.

2) Bidens comosus, leafy-bract beggarstick. Range: the Central and Northern Plains, and the western margin of the Eastern Woodlands from Minnesota to Missouri. A few occurrences have been documented around Oklahoma City, and the species has been recorded to the immediate west in Hemphill and Wheeler counties, Texas. However, Bidens comosus is very uncommon south of Kansas.

3) Chamaesyce nutans, eyebane. Range: most of the eastern half of the United States and southeastern Canada. The most westerly prior records on the Southern Plains are in Custer and Greer counties, Oklahoma.

4) Cocculus carolinus^u, Carolina coralbead. Range: most of the southeastern quarter of the United States. Common in the southeastern three-quarters of Oklahoma. The species has not previously been collected in Roger Mills County, but is known to occur in Custer and Washita counties.

5) Diospyros virginiana^u, persimmon. Range: most of the eastern United States, excluding the northern border states. The eastern edge of the ubiquitous distribution of the species in Oklahoma splits the state in two on a southwest (Comanche County) to northeast (Osage County) axis. Isolated populations in the spring areas of Ellis, Harper, Woods, and now Roger Mills counties could perhaps be considered disjunct.

6) Eleocharis erythropoda, bald spikerush. Range: the Mississippi River drainage basin and the northeastern United States. The species occurs in marshes west to the eastern Texas panhandle, but prior records in Oklahoma are surprisingly few (six northwest and south-central counties).

7) Erigeron modestus, High Plains fleabane. Range: western third of Kansas, southeastern quarter of Colorado, extreme western Oklahoma, western third of Texas, and eastern New Mexico. There are prior records from all of the westernmost tier of counties in Oklahoma.

8) Eupatorium perfoliatum v perfoliatum^u, boneset. Range: most of the eastern half of the United States and southeastern Canada. The species is scattered across the eastern half of the Great Plains. Regionally, it occurs no further west than Ellis and Roger Mills counties in Oklahoma and Wheeler County, Texas.

9) Forestiera pubescens, elbowbush. Range: primarily the American Southwest. The northeastern edge of the range of this species is in Oklahoma, extending from Roger Mills County to southern Blaine County and Canadian County, thence southeast to McCurtain County.

10) Hedysarum boreale, northern sweet vetch. Range: the northwestern United States and southwestern Canada, extending south into extreme northern Arizona and New Mexico, and southeastward through Colorado into the Oklahoma and Texas panhandles and extreme western Oklahoma. Previously recorded in Ellis and Roger Mills counties.

11) Helianthus tuberosus^u, Jerusalem artichoke. Range: southeastern Canada and most of the eastern United States, excepting the Gulf Coast. Jerusalem artichoke is fairly common in the eastern three quarters of Kansas, the east half of Oklahoma, and northeastern Texas. The only prior record in Oklahoma west of Interstate 35 is in Ellis County.

12) Juglans nigra^u, black walnut. Range: much of the eastern half of the United States. The species occurs sporadically throughout the main body of Oklahoma, and in Beaver County in the Oklahoma Panhandle, but the only documented occurrence in the Texas Panhandle is just across the border in Hemphill County. Black walnut is regionally most common in the eastern three-quarters of Kansas, western half of Missouri, and along the border between Iowa and Nebraska. See discussion above; this is possibly a Native American introduction to the study area.

13) Melampodium leucanthum, Plains blackfoot daisy. Range: the western Southern Plains south to central and southwest Texas, Chihuahua, Coahuila; west to Arizona. Not known to occur east of Roger Mills County.

14) Mirabilis glabra, smooth four o'clock. Range: the American Southwest and the western Southern Plains. There are prior records in all four of the easternmost counties of the Texas Panhandle, but the only prior record in Oklahoma is in Cimarron County.

15) Muhlenbergia sobolifera^u, rock muhly. Range: much of the eastern United States and southeastern Canada. Regionally most common in eastern Kansas and western Missouri, the species is scattered across Oklahoma, mostly the eastern two-thirds. The only two more westerly prior records are in Woods County, Oklahoma, and just across the border in Hemphill County, Texas.

16) Opuntia phaeacantha v major^u, Mojave pricklypear. Range: the American Southwest, extending into western Texas. Fairly common in the Texas Panhandle. There are scattered previously documented occurrences in Oklahoma as far east as Grady and Osage counties.

17) Quercus havardii^u, shinnery oak. Range: eastern New Mexico, northwestern Texas, and extreme western Oklahoma. In western Oklahoma, the species has been recorded in Beckham, Blaine, Cimarron, Dewey, Ellis, Harper, and Roger Mills counties.

18) Quercus havardii x stellata^u, shinnery/post oak hybrid. Range: for Q. stellata, much of the eastern United States, excluding New England and the northern Midwest. Pure post oak perhaps does not occur west of Caddo and Comanche counties in Oklahoma. The westernmost distribution of Q. stellata in western Oklahoma as mapped in Atlas of the Flora of the Great Plains (to the Texas line and across it into Hemphill County, Texas; Great Plains Flora Association 1977) is coincident with the easternmost distribution of Q. havardii. It is possible that many of the occurrences of Q. stellata mapped in western Oklahoma are in fact Q. havardii/stellata hybrids, as appears to be the case on ranch. The oaks of western Oklahoma are a puzzle. Despite apparent reproduction primarily through vegetative means, Southern Plains oaks display the genetic variation of a sexual population, and have often been interpreted as hybridizing quite freely (Mayes et al. 1998; Wiedeman and Penfound 1960). However, Muller (1951:22) believes "The freedom of hybridization ascribed to oaks is immensely over-rated." In an earlier article (1941:148) he states that "The species of Quercus are notoriously variable in trivial characters. This variability has given rise to the belief that the oak species hybridize freely." This is a situation begging a sorting-out with modern technology.

19) Quercus macrocarpa^u, bur oak. Range: most of the Mississippi River basin, extending into the northeastern United States and southeastern Canada. In Oklahoma, bur oak has previously been collected as far west as Custer, Dewey, and Washita counties, but this is the first record in the western tier of counties in the main body of the state. Quercus macrocarpa has not been documented in the Oklahoma or Texas panhandles.

20) Rhus aromatica v trilobata^u, western fragrant sumac. Range: the western half of the Great Plains. Not previously documented on the Southern Plains east of the Oklahoma and Texas panhandles.

21) Ruellia humilis, fringeleaf wild petunia. Range: from Pennsylvania and West Virginia southwest to the eastern half of Kansas, most of Oklahoma, and the northeastern quarter of Texas. The most westerly documented occurrences are in Roger Mills County and Wheeler County, Texas.

22) Smilax hispida^u, bristly greenbrier. Range: most of the eastern half of the United States. The species is fairly common in the eastern three-quarters of Oklahoma, but has not previously been documented west of Harper and Washita counties.

23) Solidago altiplanities, Llano Estacado goldenrod. Range: the southern Texas Panhandle and southwestern Oklahoma. The core distribution runs across the south half of the Texas Panhandle to Harmon and Jackson counties, Oklahoma. There are two prior outlying records, in Custer and Jefferson counties (Taylor and Taylor 1983).

24) Triodanis leptocarpa, slimpod Venus looking glass. Range: scattered over most of the Great Plains, the species is most common in the eastern two-thirds of Kansas and the western two-thirds of Missouri. It has not been previously documented in Oklahoma west of Washita County.

25) Verbena urticifolia^u, nettleleaf vervain. Range: the eastern United States and southeastern Canada. The species occurs in all of Oklahoma except the Panhandle. The westernmost regional records are just across the border in Hemphill and Wheeler counties, Texas.

26) Xanthisma texanum v drummondii, Drummond's sleepy daisy. Range: limited to the Southern Plains of eastern New Mexico, western Texas, and southern Oklahoma. The species has been collected in all of the adjoining counties to the west, south, and east of Roger Mills County, but has not previously been collected in this county.

27) Zinnia grandiflora^u, Rocky Mountain zinnia. Range: the American Southwest, parts of northern Mexico, and the west half of the Southern Plains. The species is not known to grow east of Custer and Washita counties in Oklahoma.

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Discussion: The Dempsey Divide Flora, Paleoclimate and Prehistory

We believe many of the 46 disjunct and edge-of-range taxa have both paleoenvironmental and archeological implications. There is a distinct northerly and easterly bias in their modern distributions, particularly among the plants that grow within and around the marshes at and below Brokenleg Springs, Persimmon Springs, and Sandhill Springs. Many of these plants were likely more ubiquitous and widespread before 10,000 rcy BP. In particular, we would single out Botrychium virginianum, Epilobium leptophyllum, Potentilla paradoxa, and Rudbeckia subtomentosa as likely glacial relicts. Similar relict populations of terrestrial gastropods like Gastrocopta armifera and Vertigo ovata have recently been found living at Brokenleg Springs (James L. Theler, University of Wisconsin, personal communication, 2000). These plant and snail species require a moist environment. Such conditions have apparently not been regionally common since the Late Pleistocene, when effective precipitation was much higher. Recent geoarcheological research on the Dempsey Divide has documented extensive gleyed deposits formed in marsh environments 28,000-10,000 rcy BP (Thurmond and Wyckoff 2001). Consistent with this record, modeling of Dempsey Divide paleoclimate with the Bryson model (Bryson et al. 1995) indicates a positive water balance before 10,000 rcy BP (Figure 1). The springs along the outcrop edge of the Ogallala aquifer have almost certainly served as biotic refugia during the Holocene. From an opposite perspective, the survival of these floral and gastropod taxa in marshes along the eastern outcrop edge of the Ogallala aquifer indicates that the basal Ogallala springs did not dry up during the Altithermal.

Figure 1: Comparison of modeled changes in average annual precipitation and potential evapotranspiration over the past 14,000 radiocarbon years. Note that the model indicates precipitation well in excess of evapotranspiration for the study area at the end of the last glacial (14,000-11,000 rcy BP), and near balance for the first three millennia of the current interglacial (11,000-8000 rcy BP).

Perhaps most surprising, and of greatest relevance to the archeological record, is that 258 (58.4%) of the 442 native floral taxa are ethnographically known useful plants. Some of the identified plants may have had uses we do not know about, so this should be regarded as a minimum number. Significant staple plant foods are present in abundance along the Ogallala ecotone. The oaks produce a large mast crop in some years. However, given their adaptation to upland slopes, the local oaks are highly dependent on rainfall, and their mast production varies considerably from year to year. Also, most acorns require tannin extraction for human consumption (Wandsnider 1997).

A far more reliable staple food resource for hunter-gatherers would have been cattail. Typha domingensis is the local species, at least on Brokenleg and Sergeant Major creeks on the ranch. Two other species occur on the Great Plains: T. angustifolia (which is what we initially thought we were seeing on the ranch) and T. latifolia. All are common on the Southern Plains, and apparently hybridize (Great Plains Flora Association 1991).

As indicated above, there is a base flow of fossil Ogallala aquifer water from the better springs along the Dempsey Divide, like those at the heads of Brokenleg and Sergeant Major creeks, that is not dependent on current rainfall recharge. Cattails grow around and downstream of these springs, and, given this base flow, their production is consistent from year to year. One acre of cattails will produce 6,475 lbs (2,940 kg) of flour per year on average (Harrington 1972). At present, there are 17.5 acres (7.1 ha) of cattails growing in the upper reaches of Brokenleg and Sergeant Major creeks. The acreage on these two creeks alone would produce some 55 tons (50 mt) of cattail flour per year. Such yield could not be sustainably harvested year after year, but you see the point. Along the Ogallala ecotone, cattails would have represented a productive, reliable, and easy to collect and process source of carbohydrate for prehistoric hunter-gatherers.

The subsistence attraction of the Ogallala ecotone to prehistoric hunter-gatherers is abundantly evident. Cattails, supplemented by acorns in good years, provided a virtually inexhaustible carbohydrate source. As with rice or potatoes, you might get tired of it, but you certainly would not starve. Walnuts could be crushed and boiled for fat. Bison, deer, turkey, and other small game provided protein. The other useful plants provided dietary variety; vitamins and minerals; medicines; dyes; fiber for weaving, basketry and cordage; material for atlatls and darts, bows and arrows, tool hafts, and digging sticks; and building materials.

Table 3: Modern Vascular Flora of the

Ogallala Ecotone on the Dempsey Divide

Township 12N, Range 24W; Township 13N, Range 23W, and Township 13N, Range 24W

Southern Roger Mills County, Oklahoma

The following is a list of the plants vouchered by the R.L. McGregor Herbarium of the University of Kansas and the Robert Bebb Herbarium of the University of Oklahoma as of 12/31/2001 from the Thurmond Ranch Natural Area and its immediate vicinity. Ethnographically known uses are indicated as follows: a parenthetical "c" = use as cleansing agent; "d" = use as dyeing agent; "e" = edible parts (or was used for broth, non-medicinal tea, or as a spice); "f" = use for fiber; "m" = medicinal uses; "r" = ritual uses. Assessments of use follow Cheatham et al. 1995; Elias and Dykeman 1982; Harrington 1967, 1972; Hutchens 1974; Kindscher 1987, 1992; Mabry 1977; Moerman 1986; Motley 1994; Tull 1999; and USDA Natural Resources Conservation Service 2001. Taxa marked with a plus sign (+) are not native to North America (principally following Great Plains Flora Association 1991). Those marked with an asterisk (*) were collected not on the ranch, but on adjacent properties along the Ogallala ecotone on the Dempsey Divide. In the species column, "s" = subspecies; "v" = variety; and "x" = hybrid.

Genus	Species	Common Name
Acacia	angustissima v hirta	prairie acacia (d)
Acalypha	ostryifolia	rough pod copperleaf
Acorus	calamus+	sweetflag (e, m) (Eurasian, but introduced when?)
Aegilops	cylindrica+	jointed goatgrass
Agalinis	aspera	tall false foxglove (disjunct-S of range)
Agrostis	gigantea+	spreading redtop
Allium	canadense v fraseri	Canada wild onion (d, e, m)
Allium	drummondii	Drummond's wild onion (d, e)
Amaranthus	albus	tumbleweed amaranth
Amaranthus	arenicola	sandhill pigweed
Amaranthus	blitoides	prostrate pigweed (e)
Amaranthus	palmeri	Palmer's pigweed
Amaranthus	retroflexus	rough pigweed (e)
Ambrosia	psilostachya	western ragweed (m)
Ambrosia	trifida	giant ragweed (d, e)
Ammannia	coccinea	purple toothcup
Ammannia	robusta	grand toothcup
Ammoselinum	popei	Plains sand parsley
Amorpha	canescens	lead plant (e, m)
Amorpha	fruticosa	bush wild indigo (bedding, mats, arrow shafts)
Ampelopsis	cordata	raccoon grape (e, f)
Amphiachyris	dracunculoides	prairie broomweed
Andropogon	hallii	sandhill bluestem
Androsace	occidentalis	western rock jasmine (m)
Anemone	berlandieri	tenpetal thimbleweed
Aphanostephus	skirrhobasis v skirrhobasis	parasol lazy daisy
Apocynum	cannabinum	hemp dogbane (d, f, m, r)
Argemone	polyanthemos	Plains prickly poppy (d, m)
Argythamnia	mercurialina v mercurialina*	wild mercury
Aristida	basiramea	forktip threeawn (disjunct-W of range)
Aristida	oligantha	prairie threeawn
Aristida	purpurascens v purpurascens	arrow feather threeawn (disjunct-W of range)
Aristida	purpurea v longiseta	Fendler's threeawn
Aristida	purpurea v purpurea	purple threeawn
Aristida	purpurea v wrightii	Wright's threeawn
Artemisia	campestris	western sagewort (m)
Artemisia	dracunculus	silky wormwort tarragon (m)
Artemisia	filifolia	sand sagebrush (d, m)
Artemisia	ludoviciana v ludoviciana	white sage (m, r)
Asclepias	asperula s capricornu	antelope horn milkweed (d, e, f)
Asclepias	engelmanniana	Engelmann's milkweed (e, f)
Asclepias