870 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
DESCRIPTION. 
A smooth, cespitose, half-prostrate or spreading perennial; culms ascending, seldom 
geniculate or branched, 20 to 30 cm. long; sheaths striate, smooth, close; blades nar- 
row, involute, short, only 4 or 5 cm. long, with a narrow ligular fringe of white hairs; 
spike always solitary and terminal, 4 to 5 cm. long, revolute 
toward maturity; spikelets 50 to 70, pectinate, about 6 mm. 
long, consisting of 
a lower floret and 
anupperrudiment; 
glumessmooth, not 
sharply keeled, 
rounded to abrupt- 
ly pointed, awn- 
less, the lower 3.3 
mm., the upper 5.3 
mm, long; lemma 
densely hairy, 5.5 
mm. long, with 3 
equal awns and 4 
lobes, the two cen- 
tral lobes being 
Fic. 31.—Bouteloua scor pio- nearly as long as 
ides. a, Spikelet; b,c,lem- the awns, the lat- 
maand palet of first floret; 
d, e, rudimentary lemma eral lobes short and 
and palet of second floret; attached nearly the 
f,rudiment of third floret. entire length to the 
Tron Pringle s820. 75. Jateral awns; palet 
as long as the lem- 
ma, truncate, awnless; rudiment 5.5 mm. 
long, hairy-tufted, with 3 equal scabrous 
awns and 2 axillary scales representing the 
lobes of the lemma; caryopsis not seen. 
(FicurEs 31, 32.) 
This species is as uniformly 1l-spiked as 
is B, procumbens, In other respects the 
herbarium material bears a close similarity 
to some single-spiked forms of B. gracilis. 
On the whole, however, the plants as well 
as the glumes are smoother and the spikes 
are longer, heavier, and more revolute. In 
the field the difference is still more strik- 
ing. In this species the larger plants grow 
in more conspicuous bunches and are more ; 
spreading, and the general aspect, owing Fia. 32.—Routeloua scorpioides. a, Spike; b, spike- 
to this fact and the lack of pubescence, ig let;c, d, lemma and palet of first floret; e, rudi- 
entirely different. One-spiked forms of B. ment. a, Scale 1; b, scale 5; c-e, scale 10. From 
“ys Griffiths 8527. 
gracilis are not at all uncommon. Such 
forms might easily be confused with B. scorpioides by one who had never seen the 
latter in the field. The range of B. scorpioides, however, is apparently limited to the 
high plateau of central Mexico. One-spiked forms that have been examined from 
northern Mexico or the United States can not be referred to this species. 
When Pringle’s no. 8820, from Zontecomate Station, Hidalgo, Mexico, was first 
seen it was thought that it was a distinct species. Pittier’s no. 422, from the State of 
ge 
