Poa. GRAMLNE^E. 31 1 



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

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

 be characteristic of this species. * 



50. POA, Linn. MEADOW-GRASS. 



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

 faint, 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 dioecious. 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 best authorities estimate the species at less than half that number. The mountain 

 species are 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 aud weather-worn or otherwise too imperfect for satisfactory 

 determination. 



Root annual. 1. P. ANNUA. 



Hoot perennial : flowers perfect. 



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-flowered erect branches. 4. P. ABBUEVIATA. 



Tall (1 to 3 feet), the branches 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. TRIVIALIS. 



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



Tall ; branches of the panicle solitary or in pairs. 



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



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



Root perennial : flowers dioecious, in crowded ovoid heads. 10. P. DOUGLASII. 



1. Soot annual ; culms low (rarely over 6 inches) ; branches of the short pani- 

 cle single or in pairs. 



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

 green, short, obtuse, sometimes wavy, and with the sheaths smooth : panicle often 

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

 mostly hairy below the middle. Reichenb. Icon. Fl. Germ. t. 155. 



San Diego (Cooper, Parry) ; Monterey (Brewer) ; San Francisco, Bigelow, Bolander. Found 

 all over EurojK?, in Asia, Northern Africa, Australia, etc. No doubt introduced 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 spikelets 

 and is of a much paler green, but was referred by Munro to this 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 germinating in the fall and the young plants commencing to bloom very 

 early the next spring. 



