Poa. GKAMINE.E. 311 



is unlike any otlicr species in the |icculiai- roughness of tlui lower palet nuil in the character of 

 the panicle. The puhescenco upon the ligule is also something very unusual and it may prove to 

 be characteristic of this species. 



50. POA, Linn. Mkadow-Guass. 



Panicle generally open, its rays in pairs or in half whorls. Spikelets 2-several- 

 llowered, ovate or lanceolate, compressed. Glumes mostly shorter (longer in one or 

 two species) than the lower Uorets, the lower 1 -nerved, the upper and larger 3-nerved, 

 acute or obtuse, keeled. Lower palet herbaceous or membrano-herbaceous with 

 scarious margins and tip, compressed-keeled, acute, pointless (save in two or three 

 exceptional species), 5- (rarely indistinctly 7-) nerved, the intermediate nerves often 

 fiiint, usually softly hairy at base especially on the dorsal and marginal nerves, and 

 often with crisped cobwebby hairs below. Stamens 2 or 3. Scales acute. Ovary 

 (except in one anomalous species) smooth : styles generally very short, terminal ; 

 stigmas mostly simply plumose. Grain oblong, smooth, free. 



All of our species, save one, are perennials, and one species is dicccious. They arc mostly 

 natives of cold and tenii)erate climates, and as they generally have a wide range and vary greatly 

 from local influences there is much confusion among them. Steudel brings together some 200 

 names, but the best authorities estimate the species at less than half that number. The mountain 

 species aio especially variable and present many puzzling forms. Some of the most valued pas- 

 ture grasses belong to this genus. 



It is probable that the student of the grasses of California will meet with species of Poa not 

 here described. The various collections at hand contain several forms which no doubt belong to 

 this genus, but the material is old and weather-worn or otherwise too imjpcrfect for satisfactory 

 determination. 



Root annual. 1. P. annua. 



Koot perennial : flowers jiorfect. 



Low tufted mountain or alpine species. 



Leaves short, flat and soft. 2. P. alpina. 



Leaves narrowly linear or setaceous. 



Panicle lax, one-sided and nodding. 3. P. laxa. 



Panicle with few-ilowered erect blanches. 4. P. abbkeviata. 



Tall (1 to 3 feet), the branches of the loose open i)anicle mostly in fives : 

 florets jnore or less webbed at base. Meadow or woodland grasses 

 introduced by cultivation ami (except n. 6) indigenous. 

 Culms with running rootstocks and emitting stolons. 5. P. rjiATENSl.s. 



Culms tufted, without distinct running rootstocks or stolons. 



Leaves and sheaths rough. 6. P. TIIIVIALIS. 



Leaves and sheaths soft and smooth. 7. P. SEliOTlNA. 



Tall ; branches of the panicle solitary or in pairs. 



Panicle open, the branches slcn(ler and spreading. 8. P. stenaxtua. 



Panicle narrow, the branches short and erect. 9. P. olumaris. 



Koot perennial : flowers dioecious, in crowded ovoid heads. 10. P. Douglasii. 



§ 1. Root annual) culms low (rarel;/ over 6 inches) ; branches of the short pani- 

 cle slufjle or in pairs. 



1. P. annua, Linn. Culms compressed, geniculate below, weak : leaves bright 

 green, short, obtuse, sometimes Avavy, and witli the sheaths smooth : panicle often 

 1-sided; spikelets very short-pedicelled, 3 - 7-(lowered, about 2 lines long; florets 

 mostly liairy below the midille. — Keichenb. Icon. Fl. Germ. t. 155. 



San Diego {Cooper, Parn/) ; Monterey {Brnrer) ; San Francisco, liitjrhw, Bolnndcr. Found 

 all over Europe, in Asia, Northern Africa, Australia, etc. No doubt introduced upon the coast, 

 but apparently in<ligenous in Arizona, N.-w Mexico, Western Texas, etc. The plant from these 

 inhind localities is often a foot high with verv slender culms ; it has lewer and broader spikelets 

 and is of a nuich paler green, but was refene.l by Munro to this species. IJolander s n. 1549 lias 

 largiT and more luominently nerved florets than usual. This species is what is known as a 

 winter-annual, its seeds germinating in the fall and the young plants comniencing to bloom very 

 early the next spring. 



