172 



POACEAE 



the spikelet, 3-nerved; lemmas 5-nerved. hairy on the callus, the lower 'bearing near the 

 base a twisted, geniculate, exserted awn, the upper bearing a short straight slender awn just 

 below the tip. Perennial rather tall grasses, with flat blades and rather dense panicles. 

 [Greek, masculine-awn, in reference to the awned staminate flower.] 



Species about 6 in the temperate regions of Eurasia; one species introduced into the United States. 

 Type species, Arrlieuatheruvi avcnaceum Beauv. 



1. Arrhenatherum elatius (L.) ]\Iert. & Koch. 

 Tall Oat-grass. Fig. 389. 



Avena elatior L. Sp. PI. 79. 1753. 



Arrhenatherum avenacettm Beauv. Ess. Agrost. 55, 152. pi. 11. 



f. 5. 1812. 

 Arrhciiatliennti clatins Mert. & Koch, Deutsch. FI. 1: 546. 1S23. 



Perennial; culms erect, smooth, 1-1.5 meters tall; 

 blades flat, scabrous on both surfaces, 5-10 mm. wide ; 

 panicle pale or purplish, shining, narrow, 15-30 cm. long, 

 the short branches verticillate, usually spikelet-bearing 

 from the base; spikelets 7-8 mm. long; glumes minutely 

 scabrous, the second about equaling the florets ; lemmas 

 scabrous, the awn of the staminate floret about twice the 

 length of its lemma. 



A native of Europe, cultivated occasionally as a meadow grass; 

 escaped along roadsides in a few localities in our range. June- 

 July. Type locality, European. 



41. DANTHONIA Lam. & DC. Fl. Franc, ed. 3, 3 : 32. 1805. 



Spikelets several-flowered, the rachilla readily disarticulating above the glumes and be- 

 tween the florets ; glumes about equal, broad and papery, acute, mostly exceeding the 

 uppermost floret; lemmas rounded on the back, obscurely several-nerved, bearing at base 

 a strong callus, the apex bifid, the lobes acute, usually extending into a slender awn, a 

 stout awn arising from between the lobes, the awn flat, twisted, geniculate, exserted. 

 Tufted low or moderately tall perennials, with few-flowered open or spikelike panicles of 

 rather large spikelets. [Named for fitienne Danthoine, a French botanist.] 



Species about 100 in the temperate regions of both hemispheres. Type species, Arena spicata L. 



Panicle narrow and spikelike. 

 Lemmas glabrous on the back. 

 Lemmas sparsely villous on the back. 

 Panicle open, the few branches spreading at anthesis, or reduced to a single spikelet. 

 Spikelets solitary or rarely 2. 

 Spikelets 2 to several. 

 Sheaths pubescent. 

 Sheaths glabrous. 



1. D. intermedia. 



2. D. thermalc. 



3. D. unispicata. 



4. D. americana. 



5. D. calif omica. 



1. Danthonia intermedia X'asey. 

 Mountain Wild Oat-grass. Fig. 390. 



Danthonia intermedia Vasey, Bull. Torrev Club 10: 52. 



1883. 

 Mcrathrepta intermedia Piper, Contr. U. S. Xat. Herb. 11: 



122. 1906. 



Culms 15-40 cm. tall ; sheaths smooth ; blades be- 

 coming involute, more or less pilose ; panicle narrow, 

 compact, often 1-sided, 2.5-5 cm. long, the pedicels 

 short and appressed ; glumes about 12 nun. long; 

 lemmas similar to those of D. americana, the teeth 

 more gradually acuminate, the awns shorter, the 

 dorsal awn flat, tightly twisted below, slightly 

 twisted above ; callus long, and pilose. 



Mountain meadows of the Alpine Zone; British Columbia 

 to California and Colorado. July-Aug. Type locality: Mount 

 Albert, Lower Canada. 



Danthonia intermedia cusickii Williams, L'. S. Dept. Agr. 

 Div. Agrost. Circ. 30: 7. 1901. Merathrepta intermedia 

 cusickii Piper, Contr. U. S. Nat. Herb. U: 122. 1906. 

 Differs in having larger and glabrous blades, usually stouter 

 and taller culms, and rather larger spikelets. 



British Columbia to Oregon and Wyoming, Type locality: 

 eastern Oregon. 



