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MISC. PUBLICATION 200, U. S. DEPT. OF AGRICULTURE 



mm long, the teeth setaceous, the hairs of the callus 0.5 to 1 mm long, 

 of the rachilla as much as 2 mm long, the awns slender, curved, 

 flexuous or loosely spiral, mostly 5 to 10 mm long, attached 1 to 2 mm 

 below tip. 91 — Moist woods, Alberta to southeastern Alaska, 

 south to western Montana and northern California (fig. 558). 



5. Trisetum spicatum (L.) Richt. 

 Spike trisetum. (Fig. 559, A.) Culms 

 densely tufted, erect, 15 to 50 cm tall, 

 glabrous to puberulent; sheaths and 

 usually the blades puberulent; panicle 

 dense, usually spikelike, often inter- 

 rupted at base, pale or often dark-purple, 



Figure 556.— Trisetum orthochaetum. 

 Panicle, X 1; glumes and floret, X 5. 

 (Type.) 



Figure 557. — Trisetum cernuum. Panicle, X 1; glumes 

 and floret, X 5. (Elmer 1946, Wash.) 



5 to 15 cm long ; spikelets 4 to 6 mm long; glumes somewhat unequal in 

 length, glabrous or scabrous except the keels, or sometimes pilose, the 

 first narrow, acuminate, 1-nerved, the second broader, acute, 3- 

 nerved; lemmas scaberulous, 5 mm long, the first longer than the 

 glumes, the teeth setaceous; awn attached about one third below 

 the tip, 5 to 6 mm long, geniculate, exserted. 

 91 — Alpine meadows and slopes, Arctic Amer- 

 ica, southward to Connecticut, Pennsylvania, 

 northern Michigan and Minnesota, in the 

 mountains to New Mexico and California; also 

 on Roan Mountain, N. C. (fig. 560) ; high moun- 

 tains through Mexico to the antarctic regions 

 of South America; arctic and alpine regions 

 of the Old World. In northern regions the 

 species descends to low altitudes. Exceedingly variable; several 

 varieties have been proposed, but the characters used to differentiate 

 them are variable and are not correlated. Two rather more out- 

 standing varieties, both intergrading with the species are: T. spicatum 

 var. molle (Michx.) Beal, with densely pubescent foliage, and T. 

 spicatum var. congdoni (Scribn. and Merr.) Hitchc, a nearly glabrous 

 alpine form with slightly larger spikelets. 



Figure 558.— Distribution of 

 Trisetum cernuum. 



