HOW TO KNOW THE GRASSES 



17b. Spikelets (without the awn) less than 3 mm. long; leaves thread- 

 like; some leaf blades on the culms. Fig. 203. 



Oryzopsis micrantha (Trin. & Rupr.) Thurb. 



Perennial; in dense tufts; culms thin, 30 — 

 70 cm. tall; leaf blades flat or rolled, less than 

 2 mm. wide, scabrous; panicles 10 — 15 cm. 

 long, with slender spreading branches, the 

 spikelets borne near the tips; glumes thin and 

 translucent; lemmas smooth or with oppressed 

 hairs, yellow or brownish; awns readily de- 

 tachable, straight, 5 — 10 mm. long. Open 

 woods and dry rocky slopes, intermediate ele- 

 vations. The plants are said to have some 

 forage value. June — July. 



Oryzopsis miliacea (L.) Benth. (SMILO 

 GRASS) has similar spikelets but broad, flat 

 leaf blades, 8 — 10 mm. wide. It is cultivated 

 for forage in California. Introduced from 

 Europe 



Figure 203 



18a. Lemma 5 — 12 mm. long, excluding the awn 19 



18b. Lemma 15 — 25 mm. long. Fig. 204. 

 PORCUPINE GRASS 



Stipa spariea Trin. 



Perennial; culms in small hard tufts, about 

 1 m. tall. The panicle is erect or nodding, 

 with few spikelets; glumes whitish; mature 

 lemmas brown; awns 15 — 20 cm. long, with 

 one or two sharp bends. The floret of Stipa 

 species is a remarkable self-planting device. 

 When it falls from the glumes, its sharp 

 pointed callus readily penetrates the ground. 

 The backward-pointing hairs prevent the flor- 

 et from pulling out. The twisted portion of 

 the awn coils and uncoils as the moisture 

 content of the air changes, causing the bent 

 arm of the awn to revolve slowly until it 

 comes in contact with grass stems or other 

 objects. Then the whole lemma is hterally 

 screwed down into the earth. Unfortimately 

 the same process will occur if the florets get into wool or hair of ani- 

 mals, and these florets can thus cause serious puncture wounds on 

 grazing animals, especially around the eyes, nose, and mouth. Prairies 

 and dry open groimd, mostly in the Midwest. June — July. 



Figure 204 



109 



