Poa. GRAMINE.E. 311 



is unlike any other species in the peculiar roughness of the lower palet and in the character of 

 tlie panicle. Tiie pul)csc;en(-e upon the ligule is also something very unusual and it may prove to 

 be characteristic of this species. 



50. POA, Linn. Meadow-Giiass. 



Panicle generally open, its rays in pairs or in half wliorls. Spikelcts 2 -several- 

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

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

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

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

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

 fliint, 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 dicecious. They are mostly 

 natives of cold and temperate 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 hest autlioritics estimate the species at less than half that number. The mountain 

 species are espicjally vuiialilf and present many puzzliug forms. Some of the most valued pas- 

 ture grasses lieluni,' to tliis genus. 



It is probable that the stu(h!nt of tlie grasses of California will meet with species of Pua 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 imperfect for satisfactory 

 determination. 



Root annual. 1. P. annua. 



Root perennial : flowers perfect. 



Low tufted mountain or alpine sjiecies. 



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-flowered erect branches. 4. P. adbueviata. 



Tall (1 to 3 feet), the brandies of the loose open panicle mostly in fives : 

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

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

 Culms with running rootstocks and emitting stolons. 5. P. pratensis. 



Culms tufted, without distinct running rootstocks or stolons. 



Leaves and sheaths rough. 6. P. tkivialis. 



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



Tall ; branches of the panicle solitary or in pairs. 



Panicle open, the branches slender and spreading. 8. P. stenantha. 



Panicle narrow, the branches sliort and erect. 9. P. glumaihs. 



Root perennial : flowers diojcious, in crowded ovoid heads. 10. P. Douglasii. 



§ 1. Boot annual ; culms loiv (rarely over 6 inches) ; branches of the short 2y(ini- 

 cle sbigle or in jyairs. 



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

 green, short, obtuse, sometimes wavy, and with the sheaths smooth : jianicle ofti'U 

 1-sided ; spikelets very short-pedicelled, 3 - 7-flowered, about 2 lines long ; Ihnvts 

 mostly hairy below the middle. — Reichenb. Icon. Fl. Germ. t. 15.5. 



San Diego {Cooper, Parry) ; Monterey {Breivcr) ; San Francisco, Bigeloiv, Bolaadcr. Fouiul 

 all over Euro])e, in Asia, Northern Africa, Australia, etc;. No doubt introdiiced upon the coast, 

 but apparently indigenous in Arizona, New Mexico, Western Texas, etc. The plant from these 

 inland localities is often a foot high with very slender culms ; it has fewer and broader spiUelets 

 and is of a much paler green, but was referred by Munro to tliis species. Bolander's n. 1549 has 

 larger and more prominently nerved florets than usual. This species is what is known as a 

 winter-annual, its seeds gernunating in the fall and the young plants commencing to bloom very 

 early the next spring. 



