Heads 12–20-flowered, radiate; the rays about 5, fertile (white). Involucre somewhat cylindrical or club-shaped; the scales closely imbricated in several rows, cartilaginous and whitish, appressed, with short and abrupt often spreading green tips. Receptacle alveolate-toothed. Achenes short, inversely pyramidal, very silky; pappus simple, of numerous capillary bristles.—Perennial tufted herbs (1–2° high), with sessile somewhat 3-nerved leaves, and small heads mostly in little clusters, disposed in a flat corymb. Disk-flowers pale yellow. (Name from σηρικός, silky, and καρπός, fruit.)
[*] Pappus rusty; leaves sparingly serrate, veiny, rather thin.
1. S. conyzoìdes, Nees. Somewhat pubescent; leaves oblong-lanceolate or the lower spatulate, ciliate; heads rather loosely corymbed, obconical (4–6´´ long).—Dry ground; Maine to Ohio, and southward. July.
[*][*] Pappus white; leaves entire, obscurely veined, firmer and smaller.
2 S. solidagíneus, Nees. Smooth, slender; leaves linear, rigid, obtuse, with rough margins, tapering to the base; heads narrow (3´´ long), in close clusters, few-flowered.—Thickets, S. New Eng. to Tenn., and southward. July.
3. S. tortifòlius, Nees. Hoary-pubescent; leaves obovate or oblong-spatulate, short (½–1´ long), vertical, both sides alike; heads rather loosely corymbed, obovoid (4–5´´ long).—Pine woods, Va. and southward. Aug.
25. ÁSTER, L. Starwort. Aster.
Heads many-flowered, radiate; the ray-flowers in a single series, fertile. Scales of the involucre more or less imbricated, usually with herbaceous or leaf-like tips. Receptacle flat, alveolate. Achenes more or less flattened; pappus simple, of capillary bristles (double in §§ 4 and 5).—Perennial herbs (annual only in §§ 7 and 8), with corymbed, panicled, or racemose heads; flowering in autumn. Rays white, purple, or blue; the disk yellow, often changing to purple. (Name ἀστήρ, a star, from the radiate heads of flowers.)
Conspectus of Groups.
Annuals, with copious fine soft pappus 53, 54