This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol3", 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..
Stems erect, delicate, closely tufted, 1°-2° high, glabrous, reddish brown, terete. Leaves all petioled, glabrate, very thin, but firm and crisp, the lower and basal ones oval, rounded, or with a small deep and rounded sinus at the base, bluntly acute or short-acuminate at the apex, crenate-serrate, the upper ones sometimes ovate-lanceolate, the uppermost short-elliptic; petioles slender, the uppermost sometimes winged; inflorescence 5' broad, or less, usually of about 5 convex glomerules, each often of 10-15 short-peduncled heads, its branches spreading, 3' long, or less; rays chiefly 6, white; disk at first golden yellow, finally deep purplish crimson; florets broadly bell-shaped; outer bracts obtuse, ciliate, pale, with a green tip; achenes glabrous.
On shaded rocks, near Yonkers, N. Y. Peculiar in its dense glomerules subtended by large short-elliptic leaves, but probably a race of A. divaricatus L. September.
Stems solitary or scattered, glabrate, striate, about 30 high. Leaves very thin and smooth, slender-petioled, broadly oblong, coarsely toothed with remote acuminate teeth, abruptly long-acuminate at the apex, the basal sinus broad, rounded, shallow, except in the lowest ones; leaves of the inflorescence lanceolate, subentire, sessile, sometimes 4' long; inflorescence broadly corymbose, heads about 4' high, often 1/4' broad; rays usually 9-12; disk pale yellow, becoming purplish brown, the florets funnelform with a long slender tube; outer bracts chiefly elongated-triangular, acute, green, the others linear, obtusish, the green tip lance-linear; achenes generally glabrous.
In moist dark woodlands, New York to Virginia. Peculiar in its large dark leaves with coarser teeth than in the next species. Aug.-Sept.
Aster divaricatus L. Sp. Pl. 873. 1753.
Aster corymbosus Ait. Hort. Kew. 3: 207. 1789.
Stems tufted, assurgent, flexuous, brittle, terete, 1 1/2°-2 1/2° high, glabrate at maturity. Leaves thin, smoothish, slender-petioled, ovate-lanceolate, dentate with sharp teeth, or the small basal ones coarsely serrate, acute to acuminate, the basal sinus broad or narrow; leaves of the inflorescence small, ovate and acute to orbicular; corymb broad, flattish, repeatedly forked, the slender branches long, divergent; heads 9"-12" broad; rays chiefly 6-9, linear, white; disk turning brown; bracts of the involucre broad, ciliate, the rounded tip with an inconspicuous green spot.
In open woodlands and thickets, in rather dry soil, Quebec to Manitoba, Georgia and Tennessee. Here regarded as consisting of many slightly differing races, a number of which have been considered species and varieties. Sept.-Oct.
Aster viridis Nees, remarkable for its coarse rough basal leaves, and large oval rhomboid rameal ones, occasionally from New York and Pennsylvania to Virginia, may prove to be a hybrid between the preceding and A. macrophyllus L.