DESCEIPTIONS OF SPECIES. 



29 



Texas bluegrass seed in commerce is unrubbed, and as the silky 

 pubescence and web are very persistent they are always present. The 

 hairs are so long and copious that the seeds cling in loosely matted, 

 woolly bunches, and thus are easily distinguished 

 from all the other commercial Poas. (Fig. 10.) 



Poa annua L. 



ANNUAL MEADOW GRASS. 



Spikelets 3-5 flowered; florets l|-3 mm. long, ovate or 

 ovate-lanceolate and relatively robust, strongly keeled and 

 arched at the back, more or less densely pubescent, light 

 brown or dark brown and often purplish or yellowish; 

 margins of the glume very narrowly infolded below the 

 middle, thin and broadly hyaline above the middle in the 

 lower florets, flaring, gaping, or infolded at the apex ; inter- 

 mediate veins usually distinct as narrow ridges extending 

 from the base to the margin of the apex, glabrous or jDubescent; marginal vems 

 and keel densely soft-pubescent below the middle; surface between the veins some- 

 times more or less pubescent at the base; web wanting; palea somewhat shorter than 

 the glume, except in the terminal floret; keels of the palea coarse and prominent, 

 mostly exposed, usually arched forward and exposed to side view in florets having a 

 well-developed grain, often contracted toward the rachilla segment at the base, silky 

 pubescent from near the base nearly to the apex; rachilla segment glabrous, from 

 one-fourth to one-third the length of the glume, aborted floret of the sterile rachilla 

 segment minute; grain 1-1^ mm. long, robust, distinctly granular, keeled and grooved, 

 slightly translucent. (Fig. 11.) 



The seed of Poa annua is not in the trade and is not apt to become 

 mixed with the commercial bluegrass seeds. It may be readily distin- 

 guished from the common commercial species of Poa by its abundant 



Fig. 10.— a cluster of Texas 

 bluegrass seeds matted by 

 the webbv fibers. 



Fig. 11.— Seeds of annual meadow grass {Foa annua): a and b, back views; c-e, side views; f-i, front 



views; i, a terminal floret. 



pubescence, arched and silk}- pubescent keels of the palea, and robust 

 form. The seed most closely resembles that of Poa alpma, from which 

 it is distinguished in individual seeds by its distinct intermediate veins 

 and prominent, arched, and silky pubescent but not hispid-ciliate palea 

 keels. 



Poa alpina L. 



ALPINE MEADOW GRASS. 



Spikelets 3-6 flowered; florets 2J-3J mm. long, ovate-lanceolate or obovate, the 

 uppermost lanceolate, broadly keeled, arched, acute, or obtuse, light brown, some- 

 times purplish, and often yellowish tinged at the apex; margins narrowly infolded 

 below the middle and becoming broadly hyaline at the apex; intermediate veins 



