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..
Generally perennial grasses, of various habit, with flat leaf-blades and paniculate inflorescence. Spikelets 1-flowered, the rachilla usually prolonged beyond the flower and pubescent. Scales 3; the 2 outer empty, carinate, membranous; the third scale hyaline, shorter than the outer, obtuse, usually copiously long-hairy at the base, or rarely the hairs scanty or short, and bearing a straight, bent or twisted dorsal awn; palet shorter, 2-nerved. Stamens 3. Styles short, distinct. Stigmas plumose. Grain free, enclosed in the scale. Seed adherent to the pericarp. [Greek, signifying Reed-grass.]
A genus of about 150 species, widely distributed throughout temperate and mountainous regions, and particularly numerous in the Andes. Besides the following, some 25 others occur in the western parts of North America. The English name Small-reed is applied to any of the species. Type species: Arundo Calamagrostis L.
Prolongation of the rachilla hairy its whole length.
Awn strongly bent, exserted, hairs of the callus usually much shorter than the scale.
Leaf-sheaths naked at the summit, rarely bearded; panicle tinged with purple; empty scales rather thick.
Basal hairs 1/4 as long as the flowering scale or less.
Basal hairs about 1/2-2/3, as long as the flowering scale.
Leaf-sheaths bearded at the summit; panicle pale; empty scales thin.
Spikelets 2"-3" long; callus hairs sparse; palet about equalling the scale
Spikelets 1 3/4"-2" long; callus hairs copious; palet shorter than the scale.
Awn straight, included, hairs of the callus little if any shorter than the scale.
Panicle open, the lower rays widely spreading.
Spikelets 2"-3," long, very acuminate.
Spikelets 1 1/2"-2" long; panicle usually loosely flowered.
Spikelets 1"-i 1/4" long; panicle rather densely flowered.
Panicle more or less contracted.
Culms and almost filiform leaf-blades soft, not rigid.
Culms and wide leaf-blades hard, rigid.
Panicle elongated, loosely flowered; culms not tufted, or little so.
Panicle short, dense and spike-like; culms strongly tufted.
Panicle narrow, much interrupted below; awn much shorter than the scale.
Panicle thick, continuous, or little interrupted; awn about equalling the scale.
Prolongation of the rachilla hairy only at the summit.