This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol1", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
[Eatonia Endlich. Gen. 99. 1837. Not Raf. 1819.]
Tufted perennial grasses, with flat or involute leaf-blades and usually contracted panicles. Spikelets 2-3-flowered, the rachilla extended beyond the flowers. Two lower scales empty, shorter than the spikelet, the first linear, acute, 1-nerved, the second much broader, 3-nerved, obtuse or rounded at the apex, or sometimes acute, the margins scarious; flowering scales narrower, generally obtuse. Palet narrow, 2-nerved. Stamens 3. Styles distinct, short. Stigmas plumose. Grain free, loosely enclosed in the scale and palet. [Greek, referring to the wedge-shaped second scale of the spikelet.]
Empty scales unequal, the first shorter and about one-sixth as wide as the second.
Second scale obovate, often almost truncate.
Second scale oblanceolate, obtuse or abruptly acute.
Empty scales equal, the first not less than one-third as wide as the second.
Culms i°-2 1/2° tall, erect, simple, often stout, smooth and glabrous. Sheaths shorter than the internodes, usually more or less rough, sometimes pubescent; ligule 1/2"-1" long; blades 1'-9' long, 1"-4" wide, scabrous; panicle 2'-6' in length, dense and generally spike-like, strict, the branches 1 1/2' long or less, erect; spikelets crowded, 1 1/4"- 1 1/2" long; empty scales unequal, often purplish, the first narrow, shorter than and about one-sixth as wide as the obtuse or almost truncate second one; flowering scales narrow, obtuse, 3/4"-1" long.
In dry soil, Maine to Saskatchewan, Florida and Arizona. Prairie-grass. June-Aug.
Aira pallens Spreng. Fl. Hal. Mant. 33. 1807. Eatonia pennsylvanica A. Gray, Man. Ed. 2, 558, in part. 1856. S. pallens Scribn. Rhodora 8: 145. 1906.
Usually glabrous, culms 1°-3° tall, erect, simple, slender, smooth. Sheaths shorter than the internodes; ligule 3/4" long; blades 2 1/2'-7' long, 1"-3" wide, rough; panicle 3'-/ in length, contracted, often nodding, lax, its branches 1'-2 1/2' long; spikelets 1 1/2"-1 3/4" long, usually numerous, somewhat crowded and appressed to the branches; empty scales unequal, the first narrow, shorter than and about one-sixth as broad as the obtuse or abruptly acute second one, which is smooth, or somewhat rough on the keel; flowering scales narrow, acute, 1 1/4" long, rarely awned.
In hilly woods or moist soil, Newfoundland to British Columbia, Georgia and Texas. June-July.
Aira nitida Spreng. Fl. Hal. Mant. 32. 1807. Eatonia Dudleyi Vasey, Coult. Bot. Gaz. 11: 116. 1886. Eatonia nitida Nash, Bull. Torr. Club 22: 511. 1895. E. glabra Nash, in Britt. Man. 1043. 1901. S. nitida Scribn. Rhodora 8: 144. 1906.
Glabrous, culms 1°-2° tall, erect, very slender, smooth. Sheaths shorter than the internodes, generally pubescent; ligule 1/4" long; blades ¥-3' long, 1" wide or less, often pubescent, the uppermost very short; panicle 2'-6' in length, lax, the branches spreading at flowering time, afterwards erect, l'-2 1/2' long; spikelets not crowded, 1 1/2" long; empty scales smooth, the first about one-third as wide as and equalling the second, which is obtuse or almost truncate, often apiculate; flowering scales narrow, 1"-1 1/4" long, obtuse or acutish, smooth.
In dry woods. Vermont to Michigan, Georgia and Mississippi. May-June.