MANUAL OF THE GRASSES OF THE UNITED STATES 445 



flexuous or geniculate, often twisted few-flowered toward the ends; spike- 

 below; palea narrow, indurate, except lets long-pediceled; glumes about 5 

 toward the margins, central keel con- mm. long, abruptly acuminate, 7- 

 sisting of two nerves and a narrow nerved; lemma a little shorter than 

 channel or sulcus between, the apex the glumes, appressed-pubescent, es- 

 of the keel projecting above the sum- pecially on the callus, dark brown at 

 mit of the lemma as a minute point, maturity with a circular ridge at the 

 Tufted perennials with narrow usu- base of the awn; awn weakly twice 

 ally involute blades and rather few- geniculate, 1 to 2 cm. long. % (Ory- 

 flowered panicles. Type species, Pip- zopsis fimbriata Hemsl.) — Open rocky 

 tochaetium setifolium Presl. Name woods, Colorado to western Texas, 

 from Greek piptein, to fall, and chaite, Arizona, and Mexico. A fine forage 

 bristle, alluding to the deciduous grass. Specimens from the United 

 awns of the type species. States and most of those from north- 

 1. Piptochaetium fimbriatum (H. ern Mexico have pale glumes (P. 

 B. K.) Hitchc. Pinyon ricegrass. fimbriatum var. confine I. M. John- 

 (Fig. 637.) Culms densely tufted, ston), while those of middle and 

 erect, slender, 40 to 80 cm. tall; southern Mexico have purple or 

 blades involute-filiform, flexuous, brown glumes, as in the type of P. 

 elongate; panicle open, 5 to 15 cm. fimbriatum. In that, 1 panicle is open 

 long, the slender branches spreading, and 2 are narrow, as in var. confine. 



91. STIPA L. Needlegrass 



Spikelets 1-flowered, disarticulating above the glumes, the articulation 

 oblique, leaving a bearded, sharp-pointed callus attached to the base of the 

 floret; glumes membranaceous, often papery, acute, acuminate, or even 

 aristate, usually long and narrow; lemma narrow, terete, firm or indurate, 

 strongly convolute, rarely the margins only meeting, terminating in a promi- 

 nent awn, the junction of body and awn evident, the awn twisted below, 

 geniculate, usually persistent; palea enclosed in the convolute lemma. Tufted 

 perennials, with usually convolute blades and mostly narrow panicles. Type 

 species, Stipa pennata L. Name from Greek stupe, tow, alluding to the feathery 

 awns of the type species. 



The species are for the most part valuable forage plants. Several, all western, 

 such as Stipa comata, S. occidentalis, S. le?nmoni, and S. neo?nexicana, are 

 grazed chiefly when young. Stipa lettermani is important at high altitudes, in 

 the mountains of the West; S. columbiana at medium altitudes; S. viridula 

 in the Rocky Mountains; S. pulchra, S. thurberiana, and S. speciosa in Cali- 

 fornia. Some of the species, when mature, particularly S. spartea and S. 

 comata, are injurious, especially to sheep, because of the hard sharp points to 

 the fruits which penetrate the skin. Sleepy grass, S. robusta, acts as a narcotic 

 (see p. 458). One of the Old World species, S. tenacissima L., furnishes a part 

 of the esparto or alfa grass of Spain and Algeria that is used in the manu- 

 facture of paper and cordage. 



la. Terminal segment of awn plumose. 



Awn 12 to 18 cm. long 1. S. necmexicana. 



Awn 1.2 to 1.5 cm. long 16. S. porteri. 



lb. Terminal segment of awn not plumose, or somewhat plumose in S. occidentalis. 

 2a. First segment of the once-geniculate awn strongly plumose, the ascending hairs 5 to 



8 mm. long 2. S. speciosa. 



2b. First segment of awn sometimes plumose but the hairs not more than 2 mm. long. 

 3a. Mature lemma 2 to 3 mm. long. Awn capillary, flexuous, about 5 cm. long. 



34. S. TENUISSIMA. 

 3b. Mature lemma at least 5 mm. long. 



