GEAMINEAE (GRASS FAMILY) 



69 



3. p. pratensis. 



4. P.flava. 



5. P. interior, i 



6. P. platyphylla. 



55. 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 , . 1. P. ainnua. 



Perennials. 



Stems flattened, 2-edgecl; panicle small . . , , 2. P. com,pressa. 

 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 oh 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 puri>le-tinged 

 Lemmas mostly greenish. 



Glumes subequal 



Glumes unequal ..... 



Flowers dioecious; mternerves glabrous. 

 Ligules short, rounded or truncate at apex. 

 Panicle narrow, long-pedimcled 

 Panicle more open, and with shorter peduncle 

 Ligules longer and acute ..... 

 Spikelets rounded (scarcely at all flattened); lemmas 

 narrow but not acute. I 



Lemmas scabrous throughout. 



Lemmas and glimies unequal; leaves narrow and 



involute 21. P. laevigata. 



Lemmas and glumes subequal; leaves broader 



and usually flat 22. P. nevadensis. 



Lemmas scabrous above only, strigose below. 

 LfeaVes pale (yellowish"), very narrow and usu- 

 ally involute 23. P. lueida, 



Le3,ves dark green. 



Leaves plicate 24. P. Buckleyana. 



Leaves 'flat , 25. P. Sheldonii. 



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. 



1. Pea annua L. Sp. PL 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, 

 acutej 1-nervedj about two thirds as Ions as the broad and obtuse 3-nerved 



