STIPA TRIODIA 363 



( 1 ) Awn long-plumy ; glumes equal, 5 mm. long 5\ mongolica 



(2) Awn rough, not plumy; glumes unequal, 



the lower 9 mm. long S.Ric hards onii 



b. Panicles narrow and spike-like 



(1) Awn long-plumy, the hairs 1-6 mm. long 



(a) Glumes 10-12 mm. long ; lemma sparsely 



hairy, 5-6 mm. long S. occidentdlis 



(b) Glumes 16-18 mm. long; lemma silky, 



10-12 mm. long S. speciosa 



(2) Awn not plumy, or at least the hairs less 



than 1 mm. long 



(a) Lemma with a tuft of hairs at the tip S.Scribneri 



(b) Lemma without a tuft of hairs at the 



tip ; stems 3-8 ft. high ; sheaths smooth 

 or hairy ; awns 2-4 cm. long S. viridula 



2. Awn 3-7 in. long 



a. Awn plumy ; glumes 3-4 cm. long 5. neo-mexicana 



b. Awn not plumy, glumes 2-3.5 cm. long 



(1) Panicle usually partly included in the 



sheath ; glumes 18-27 mm. long ; lemma 



8-12 mm. long S. comdta 



(2) Panicle not enclosed at base ; glumes 24- 



36 mm. long ; lemma 14-25 mm. long S. spdrtea 



TRIODIA Robert Brown 1810 TRIODIA 



(Gr. tri-, from the 3-pointed lemmas) 



(Tricuspis, Triplasis Beauvois) 



PI. 45, fig. 27. 



Spikelets 2-12-flowered, in racemes or panicles; glumes keeled, 1-3- 

 nerved; lemma 3-nerved, lobed or toothed at tip, the nerves hairy and usu- 

 ally extending as short points between the teeth, palet broad, 2-keeled; 

 perennial. 



1. Spikelets loosely 2-5-flowered, 5-8 mm. long; 



lemma 2-lobed at tip, the middle nerve becom- 

 ing a short awn T. purpurea 



2. Spikelets 5-12-flowered 



a. Lemma awnless, entire or 2-toothed T. mutica 



b. Lemma awned 



(1) Spikelets 6-7-flowered T.pulchella 



(2) Spikelets 8-12-flowered T. acumindta 



