12. E. perfoliàtum, L. (Thoroughwort. Boneset.) Stem stout (2–4° high), hairy; leaves lanceolate, united at the base around the stem (connate-perfoliate), tapering to a slender point, serrate, very veiny, wrinkled, downy beneath (5–8´ long); scales of the involucre linear-lanceolate.—Low grounds; common and well-known.—Varies with the heads 30–40-flowered, or with some or all of the leaves separated and truncate at base.
Var. cuneàtum, Engelm. Leaves smaller, narrowed at base and separate, and heads fewer-flowered. Perhaps a hybrid with n. 7.—Mo. and southward.
13. E. resinòsum, Torr. Minutely velvety-downy (2–3° high); leaves linear-lanceolate, elongated, serrate, partly clasping, tapering to the point, slightly veiny beneath (4–6´ long); scales of the involucre oval, obtuse.—Wet pine barrens, N. J.—Name from the copious resinous globules of the leaves.
[*][*][*] Heads 8–30-flowered; involucral scales nearly equal, in one row; leaves opposite, ovate, petioled, triple-nerved, not resinous-dotted; flowers white.
14. E. ageratoìdes, L. (White Snake-root.) Smooth, branching (3° high); leaves broadly ovate, pointed, coarsely and sharply toothed, long-petioled, thin (3–5´ long); corymbs compound.—Rich woods; common northward.
15. E. aromáticum, L. Smooth or slightly downy; stems nearly simple; leaves on short petioles, ovate, rather obtusely toothed, not pointed, thickish.—Copses, Mass. to Va., and southward, near the coast.—Lower and more slender than n. 14, with fewer, but usually larger heads; not aromatic.
§ 2. CONOCLÍNIUM. Receptacle conical; involucral scales nearly equal, somewhat imbricated.
16. E. cœlestìnum, L. (Mist-flower.) Somewhat pubescent (1–2° high), leaves opposite, petiolate, triangular-ovate and slightly heart-shaped, coarsely and bluntly toothed; heads many-flowered, in compact cymes; flowers blue or violet. (Conoclinium cœlestinum, DC.)—Rich soil, N. J. to Mich., Ill., and southward. Sept.
6. KÙHNIA, L.
Heads discoid, 10–25-flowered; flowers perfect. Involucral scales thin, few and loosely imbricated, narrow, striate-nerved. Corolla slender, 5-toothed. Achenes cylindrical, 10-striate; pappus a single row of very plumose (white) bristles.—A perennial herb, resinous-dotted, with mostly alternate leaves, and paniculate-corymbose heads of cream-colored flowers. (Dedicated to Dr. Kuhn, of Pennsylvania, who carried the living plant to Linnæus.)