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 fusiform 
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 brown to dark brown, sometimes tinged with 
purple, sterile florets lighter; glume usually sharply 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 margins 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 1; mm. 
long, somewhat keeled and grooved, often broadest below the middle, reddish brown 
or darker about the embryo, and semitranslucent. ‘Fig. 4.) 
Fig. 4.—Different forms of commercial seeds of Kentucky bluegrass (Poa pratensis): a and 6, back 
views: c-j, side views: g-j, iront views; j, a terminal floret. 
Commercial Kentucky bluegrass seed is mostly free from the silky 
and webby hairs present in hand-gathered samples, owing to the rubbing 
process to which it is subjected before being marketed. The severe 
rubbing results in more or less injury to the thin margins of the 
olume, particularly at the apex, which is 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 evidently 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 nearly meet and are but slightly or scarcely 
distended. Such are much lighter in weight than well-developed 
seeds and consequently are mostly blown out with other chaff in well- 
cleaned seed. 
