200 A TEXT-BOOK OF GRASSES 
awn. This awn is usually tightly twisted below, the 
upper part being once or twice bent. In some species 
(S. spartea Trin.) (Fig. 36) the awn is stout and several 
inches long; in others it is beautifully plumose with silky 
hairs (S. pennata L. of 
the Russian steppes and 
S. speciosa Trin. & Rupr. 
of California). The vari- 
ous species form an 
important part of the 
forage on the plains and 
foothills of the south- 
western states and 
Mexico. The esparto- or 
alfa-grass of Spain and 
Algeria (S. tenacissima 
L.) furnishes a fiber that 
is used for paper and for 
cordage. The sleepy- 
grass (S. Vaseyi Seribn.) of Colorado and New 
Mexico because of narcotic qualities is injurious to 
horses. Two species of the Old World are said to 
be poisonous (S. inebrians Hance and S. sibirica 
Lam.). 
231. Muhlenbergia Schreb—A large genus of 
mostly American grasses, especially abundant on the 
dry uplands of the southwestern states and Mexico. 
It grades on the one hand into Sporobolus, from 
which it differs in having an awned or mucronate lemma, 
and on the other into Epicampes, from which it differs 
in having a relatively firmer lemma. Many species are 
important constituents of the forage upon grazing areas 
in the Southwest. One species of the allied genus 
Fic. 36. Stipa spartea. 
Mature floret (fruit) with_ 
twisted awn, X1 
