GRAMINEAE (GRASS FAMILY) 



09 



65. POA L. MEADOW GRASS. SPEAR GRASS. BLUE GRASS 



Annual or perennial grasses with flat or convolute leaves and numerous 

 spikelets in contracted or open panicles. Spikelets 2-10-flowered with a 

 glumaceous rudiment, perfect, compressed, ovate, awnless, in a contracted or 

 open panicle. Glumes membranaceo-herbaceous, lance-ovate, subacute, the 

 first 1-nerved, the second 3-nerved; lemma thin, herbaceous, subacute or 

 obtuse, 5-nerved, usually pubescent on the keel and with cobwebby hairs at 

 the base, longer than the hyaline palet. Grain oblong, linear, much shorter 

 than the floret. 



Annual; lemma without cobwebby hairs at the base 

 Perennials. 



Stems flattened, 2-edged; panicle small .... 



Stems cylindrical. 



Lemma webbed, i. e., with a tuft of fine hairs at the base 



(except No. 8). 

 Panicle large. 



Its branches not reflexed. 



Lemmas acute ....... 



Lemmas obtuse. 



Broader than the second glume .... 



Not broader than the second glume 

 Its branches reflexed ...... 



Panicle small, its fruiting branches reflexed. 



Leaves more or less conduplicate .... 



Leaves flat. 



Lemma copiously pubescent on the mid- and lat- 

 eral nerves ........ 



Lemma glabrate and cobweb nearly or quite wanting 

 Lemma not webbed. 



Leaves short and broad; panicle small, open; spikelets 

 rounded at the base ...... 



Leaves normal; panicle various;, spikelets acute at base. 

 Low alpine grasses. 



Lemma pubescent on the mid- and lateral nerves . 

 Lemma glabrous ....... 



Taller grasses of subalpine or lower stations. 

 Spikelets strongly flattened; lemmas acute. 



Flowers perfect; lemmas hairy on the nerves and 



internerves. 



Plants with creeping rootstocks; panicle open. 

 Leaf-sheaths retrorsely strigose . 

 Leaf-sheaths glabrous ..... 



Plants tufted, no creeping rootstocks ; panicle 



narrow. 



Lemmas strongly purple-tinged 

 Lemmas mostly greenish. 



Glumes subequal ..... 



Glumes unequal 



Flowers dioecious; internerves glabrous. 

 Ligules short, rounded or truncate at apex. 

 Panicle narrow, long-peduncled 

 Panicle more open, and with shorter peduncle 

 Ligules longer and acute ..... 



Spikelets rounded (scarcely at all flattened); lemmas 



narrow but not acute. 

 Lemmas scabrous throughout. 



Lemmas and glumes unequal; leaves narrow and 

 involute ....... 



Lemmas and glumes subequal; leaves broader 

 and usually flat ..... 



Lemmas scabrous above only, strigose below. 

 Leaves pale (yellowish), very narrow and usu- 

 ally involute ...... 



Leaves dark green.. 



Leaves plicate ...... 



Leaves flat 



1. P. annua. 



2. P. compressa. 



3. P. pratensis. 



4. P. flava. 



5. P. interior. 



6. P. platyphylla. 



7. P. arctica. 



8. P. reflexa. 



9. P. laxa. 



10. P. alpina. 



11. P. Pattersonii. 



12. P. Lettermannii. 



13. P. Wheeleri. 



14. P. nervosa. 



15. P. subpurpurea. 



16. P. subaristata. 



17. P. epilis. 



18. P. longipedunculata. 



19. P. Fendleriana. 



20. P. longiligula. 



21. P. laevigata. 



22. P. nevadensis. 



23. P. lucida. 



24. P. Buckleyana. 



25. P. Sheldonii. 



1. Poa annua L. Sp. PI. 68. 1753. Culms 5-30 cm. tall, from an annual 

 root, erect or decumbent at base, somewhat flattened, smooth: sheaths loose, 

 usually overlapping; leaves 1.25-10 cm. long, 1.5-3 mm. wide, smooth: panicle 

 1.25-10 cm. in length, open; branches spreading, 6-35 mm. long, naked at 

 base-, spikelets. 3-5-flowered, 3-5 mm. long: glumes smooth, the first narrow, 

 acute, 1-nerved, about two thirds as long as the broad and obtuse 3-nerved 



