22 



THE SEEDS OF THE BLUEGRASSES. 



DESCRIPTIONS OF SPECIES. 



Poa pratensis L. 



KENTUCKY BLUEGRASS, JUNE GRASS. 



Spikelets 3-5 flowered; florets 2-2| mm., rarely 3 mm., long, lanceolate or fnsiforni 

 as viewed from the back, lanceolate or ovate-lanceolate as viewed from the side, 

 mostly acute or the terminal floret sometimes acuminate at the apex, glabrous 

 between the veins, varying from light lirown to dark brown, sometimes tinged with 

 purple, sterile florets lighter; glume usually sharj^ly keeled quite to the apex and 

 often strongly arched, particularly at the base; its marginal folds comparatively 

 broad, extending from the base nearly or quite to the apex, becoming hyaline-edged 

 above the middle in the lower florets, usually not expanded or flaring at the apex, 

 the edges nearly meeting in sterile florets, separated and usually distended forward 

 in fertile lower florets, often scarcely covering the palea keels of fertile terminal 

 florets, the hyaline edge more or less torn away and the margins jagged at the apex 

 in rubbed commercial seed; intermediate veins distinct and glabrous; keel and mar- 

 ginal veins silky pubescent below the middle or somewhat higher on the keel; basal 

 web well developed; pubescence and web wanting, except occasional traces of the 

 former, in well-rubbed commercial seed; palea nearly or quite as long as the glume, 

 its keels finely hispid-ciliate and usually covered for the greater part of their length 

 by the nuargins of the glume; rachilla segment slender, glabrous, varying from about 

 one-sixth of the length of the glume in the lower florets to one-half its length in the 

 terminal one; aborted floret of the. sterile rachilla segment minute; grain H mm. 

 long, somewhat keeled and grooved, often broadest below the middle, reddish brown 

 or darker about the embry(j, and semitranslucent. '^Fig. 4.) 



Fig. 4. — Different forms of commercial seeds of Kentucky bluegrass {Poa i>ratensis): a and b, back 

 views; c-/, side views; g-j, front views; j. a terminal floret. 



Commercial Kentucky bluegrass seed is mostly free from the silky 

 and webb}^ hairs present in hand-gathered samples, owing to the rub})ing 

 process to which it is subjected before being marketed. The severe 

 rubbing results in more or less injury to the thin margins of the 

 glume, particularly at the apex, which i.s usually found to be more or 

 less torn when examined with a lens. Seeds of a well-rubbed sample 

 do not tend to cling in small bunches as do those which are unrubbed 

 or hand-gathered. Well-developed seeds are rather robust and have 

 the glume margins well separated and evidentl}^ distended forward. 

 Sterile seeds, or such as have the grain wanting, or poorly developed, 

 are generally lighter colored, slenderer, and more compressed, while 

 the glume margins more nearl}- meet and are but slightly or scarcely 

 distended. Such are much lighter in weight than well-developed 

 seeds and consequentl}' are mostly blown out with other chaff in well- 

 cleaned seed. 



