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NEW A COMBINATION BOUTELOUA (POACEAE) IN JOSEPH WIPFF STANLEY JONES K. and D. (BRCH) Herbartum Botanical Research Center Box 6717 P.O. TX 77805-6717, Bryan, U.S.A. ABSTRACT & Wipff una S.D. Jones. Se ofrece clave Bouteloua hirsuta M. Lagasca Segura subsp. pectinata (H. Featherly) y J. & Wipff S.D. Jones, comb, et Stat. nov. Basionym: Bouteloua pectinata H. hmuta Fearherly, Bot. Gaz. 91:103. 1931. Bouteloua vnt. pectinata (H. Featherly) V. UNITED STATES. Oklahoma. Comanche Cory, Rhodora 38:405. 1936. Type: Co.: Aug near Fort 17 1929, B. English 71 (holotype: US). Sill, been recognized Bouteloua pectinata, closely related to B. hirsuta, has at taxonomic Roy and Gould (1971) and Gould (1975, 1979) various ranks: recognized this taxon as a distinct species; Cory (1936) recognized it as a variety of B. hirsuta; and Hitchcock (1935) and Chase (1951) treated it as a synonym of B. hirsuta without any infraspecific rank. The two taxa can be & Gould (Roy distinguished by the following characters 1971): lowermost rudimentary Tuft of trichomes present at the base of the floret; 1. 25-40 nflorescence axis c A and by Roy and Gould biosystematic study of B. pectinata B. hirsuta 971) resulted in the following conclusions: 1) B. pectinata is restricted to undisturbed calcareous and most frequent ell-drained, relatively soils is Comanche from Pontotoc and limestone outcrops, occuring thin-soiled 1 )unties, Oklahoma, south to Uvalde County, Texas; 2) Bouteloua hirsuta. 109- found wide in a variety of habitats, widely distributed and occurs from is New Wisconsin and North Dakota, south Illinois to to Louisiana, Texas, Mexico, Arizona, southern California, and northern Mexico; the mor- 3) phological uniformity of B. peainata, In = 20 populations contrasts strik- ingly to the morphological variability observed in the diploid plants 2n = hmuta 20, of B. hirsuta. Usually associated with diploid B. are plants with widely varying chromosome numbers, 2n = e.g. 22, 24, 26, 28, 30, 32, 34, 36, 40, 42, 43, 44, 45, 46, 48, 50, 52, 53, 54, 56, 58, and 60 (Roy 1968); where two 4) populations of the taxa are sympatric, swarms of putative hybrid plants are found that are intermediate in some or of the all critical morphological and most characteristics; for the part, these putative hy- 5) swarms found brid are only along the margins of typical B. pectinata sites (when populations of B. hirsuta are also present). Sites in Kendall County, Texas appear to be representative of the ecological distribution and separa- tion of the two taxa. Roy and Gould (1971) stated, "Throughout this area two the species, B. hirsuta and B. were intermingled pectinata, in slightly dis- way turbed road right of sites. Bouteloua hirsuta predominated at the base of the slopes and in the guUeys and ditches, and B. was most \sic\ pectinata abundant on and the ledges hilltops. Intermediate plants were abundant." From these data, B. pectinata restricted in geographic distribution, is its occupies a specific ecological site, and generally ecologically allopatric is and morphologically distinct from B. hirsuta. However, there are putative hybrid swarms at the boundary where the two taxa come in contact. These swarms show an integration of morphological between two characters the taxa indicating a lack of complete reproductive These data war- isolation. rant the recognition of B. pectinata at the subspecific rank. We W.E. are grateful to Fox, (TAES), Stephan Hatch (TABS), III L. AWPMRU), (USDA, Gretchen D. Jones and W. Morden Clifford for re- ArtvisionolAS CllASC,A 1951 Ilitchcocks manual of the i^nsses «1 the U: USDA US 2nd ed Misccll niKuis PliMi. 200 Government ition Prin V nmns New Cory, 19-.6 ind ikw eomhin ions h)r Texas plants Rhodora 3 it rW Gould, 19^^ The ^usso utkx kxis AcVM University Press, Colie^ is FW Gould, 19^9 The ^enus 6 (Puaee Ann Missouri Bot Gard //',//// ic) 6 AS U D Hitchcock, Manual 19^)5 oi the grasses of the United Stares S i U D neous Publication 200 S Governmenr Printing Olhte, Washington, G A Ro\, P 1968 systematic study of the Bmitdoiia hnuUa-Boutdoiia petttna A&M D Ph dissertation, Texas University College Station W G Roy, P and F Gould 97 Biosystematic investigations of Biwttloua hi 1 1 Gross morphology Southw ^77-387 pectinata Naturalist 15 I