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..
Perennial leafy herbs, the lower leaves reduced to scales or sheaths, the upper large, mostly entire, acute or acuminate in our species. Basal leaves none. Heads corymbose, usually numerous; involucre campanulate to hemispheric, its bracts imbricated in several series, appressed, thin, sometimes scarious-margined, their tips not herbaceous nor foliaceous. Receptacle foveolate. Ray-flowers white, pistillate, not very numerous. Disk-flowers perfect, the corolla with a slender tube abruptly expanded into a campanulate 5-lobed limb, white to greenish in our species. Anthers obtuse at the base; style-appendages ovate to subulate (rarely obtuse). Achenes obovoid, glabrous, or pubescent. Pappus double, the outer series of numerous short bristles or scales, the inner series of long capillary bristles, some or all of which have thickened tips. [In honor of Th. Dollinger, botanical explorer.]
Leaves lanceolate to ovate; heads mostly numerous. Leaves lanceolate to oblong-lanceolate, acuminate.
1. D. umbellata.
Leaves ovate to ovate-lanceolate, acute.
2. D. humilis.
Leaves, at least the lower, obovate; heads commonly few.
3. D. infirma.
Aster umbellatus Mill. Gard. Dict. Ed. 8, No. 22. 1768. Diplopappus umbellatus Hook. Fl. Bor. Am. 2: 22. 1834. D. umbellata Nees, Gen. & Sp. Ast. 178. 1832. Aster umbellatus var. pubens A. Gray, Syn. Fl. 1: Part 2, 197. 1884. D. pubens Rydb. Bull. Torr. Club 37: 147. 1910.
Stem glabrous or pubescent above, striate, corymbosely branched at the summit, 1°-8° high. Leaves lanceolate to oblong-lanceolate, ascending, glabrous above, usually pubescent at least on the veins beneath, membranous, acuminate at the apex, narrowed at the base into short petioles, or the uppermost sessile, hispid-margined, those of the stem 5'-6' long, 1/2'-1' wide; heads numerous, 6"-10" broad, in terminal compound corymbs; involucre broadly campanulate or hemispheric, 1 1/2"-2" high, its bracts lanceolate, usually pubescent or ciliate, acutish or obtuse, imbricated in 3 or 4 series, the outer shorter; rays 10-15, white; style-appendages ovate, acute; pappus nearly white; achenes nerved, slightly pubescent.
In moist soil, Newfoundland to Georgia, Saskatchewan, Iowa and Michigan. July-Oct.
Aster humilis Willd. Sp. Pl. 3: 2038. 1804.
D. amygdalina Nees, Gen. & Sp. Ast. 179. 1832.
Aster umbellatus var. latifolius A. Gray, Syn. Fl. 1:
Part 2, 197. 1884. Doellingeria humilis Britton, in Britt. & Brown, 111. Fl.
3: 392. 1898.
Similar to the preceding species, usually lower, seldom over 40 high; stem striate, corymbosely branched above, glabrous, or somewhat pubescent. Leaves ovate to ovate-lanceolate, rather firm, sessile, or the lower very short-petioled, acute or short-acuminate at the apex, narrowed, or sometimes rounded at the base, rough-margined, those of the stem 1'-3' long, 1/2'-2' wide, inflorescence as in D. umbellatus; pappus dirty white; achenes somewhat pubescent.
In moist soil, eastern Massachusetts to New Jersey, Pennsylvania, Florida and Texas. Perhaps a broad-leaved race of the preceding species. July-Sept.
Aster infirmus Michx. Fl. Bor. Am. 2: 109. 1803. Diplopappus cornifolius Less.; Darl. Fl. Cestr.
Stem slender, glabrous, or roughish above, sparingly branched at the summit, terete, 1 1/2°-3° high. Leaves entire, hispid-margined, glabrous above, sparingly hispid on the veins beneath, the lower obovate, small, obtuse, usually sessile, the upper larger, oblong-lanceolate, acute, 2'-5' long, 1'-1 1/2' wide; heads few, about I broad, in a divergently branched terminal corymbose cluster; involucre broadly campanulate, 2"-3" high, its bracts oblong-lanceolate, obtuse, sparingly pubescent, imbricated in about 4 series, the outer much shorter; rays 8-15, white; style-appendages subulate; pappus tawny; achenes nerved, glabrous.
In dry, usually rocky soil, Massachusetts to New York, Georgia, Tennessee and Alabama. Aug.-Sept.