HITCHCOCK—MEXICAN GRASSES. 335 
2. Trichloris pluriflora Fourn. Mex. Pl. 2: 142. 1886. 
Type locality, ‘‘Texas, inter Laredo et Bejar,” the only locality cited. 
RanGE: Texas and New Mexico to Argentina. 
HERBARIUM SPECIMENS FROM Mexico: 
CoaHuILA: Sabinas, Nelson 6827. 
Oaxaca: Tomellin, rocky soil near river, Hitchcock 6202. Rfo de Santa Lucfa, 
boundary of Oaxaca and Puebla, rocks, arroyos, Purpus 2895. 
88. BOUTELOUA Lag. Var. Cienc, 24: 134. 1805. 
GRAMA GRASS. 
KEY TO THE SPECIES. 
Plants annual. 
Spike 1.2.2... ene cence 2. B. procumbens. 
Spikes 2 or more. 
Spikelets pectinately arranged. 
Awns scarcely exceeding the spikelets............ 3. B. barbata. 
Awns exceeding the spikelets 1 mm. or more...... 4. B. arenosa. 
Spikelets not pectinately arranged. 
Leaves tuberculate-pubescent; spikes subtriangular 
in outline........2.... 0.0.2.0 e eee eee eee 5. B. alamosana. 
Leaves not tuberculate- -pubescent; spikes nearly 
linear. ... 22.22... eee eee eee eee eeeeeee 1. B. aristidoides. 
Plants perennial. 
Spike normally 1, conspicuously scorpioid. 
Plants stoloniferous.............2..22.-2---2---2-- ... 1%. B. stolonifera. 
Plants not stoloniferous................ cee eee eee 8. B. scorpioides. 
Spikes normally 2 or more. 
Plants stoloniferous; culms white-lanate............... 6. B. eriopoda. 
Plants sometimes decumbent but not stoloniferous; 
culms not lanate. 
Spikelets pectinately arranged. 
Spikes normally 2. 
Glumes tuberculate; rachis prolonged 
beyond the spikelets as a naked 
point. 
Internodes hirsute-villous. .......... 10. B. hirticulmis. 
Internodes glabrous.................- 9. B. hirsuta. 
Glumes not tuberculate; rachis not pro- 
longed. 
Culms erect, simple, annual. ........ 12. B. gracilis. 
Culms geniculate, branching, partially 
, perennial. ...............-.... 13. B. ramosa. 
Spikes normally 4 or more. 
Second glume long-pilose; spikes flexuous. 11. B. parryi. 
Second glume glabrous or scabrous only. 
Culms decumbent, rooting at the lower 
nodes. .....--.---. eee eee eee 14. B. sonorae. 
Culms erect or ascending. 
Awns twice as long as the body of 
the lemma, much exceed- 
ing the spikelet.......... 17. B. trifida. 
81544°—13——11 
