36. POLÝMNIA, L. Leaf-Cup.
Heads broad, many-flowered, radiate, rays several (rarely abortive), pistillate; disk-flowers perfect but sterile. Involucral scales in two rows; the outer about 5, leaf-like, large and spreading; the inner small and membranaceous, partly embracing the thick triangular-obovoid achenes. Receptacle flat, membranous-chaffy. Pappus none.—Tall branching perennial herbs, viscid-hairy, exhaling a heavy odor. Leaves large and thin, opposite, or the uppermost alternate, lobed, and with dilated appendages like stipules at the base. Heads in panicled corymbs. Flowers light yellow; in summer and autumn. (Dedicated to the Muse, Polyhymnia, for no obvious reason.)
1. P. Canadénsis, L. Clammy-hairy, 2–5° high; lower leaves deeply pinnatifid, the uppermost triangular-ovate and 3–5-lobed or angled, petioled; heads small; rays 5, obovate or wedge-form, shorter than the involucre, often minute or abortive, whitish-yellow; achenes 3-costate, not striate.—Moist shaded ravines, Conn. to W. Vt., Minn., and southward.—Var. radiàta, Gray; ligules more developed, 3-lobed, 3–6´´ long, whitish. Ill. to Kan., and southward.
2. P. Uvedàlia, L. Roughish-hairy, stout (4–10° high); leaves broadly ovate, angled and toothed, nearly sessile; the lower palmately lobed, abruptly narrowed into a winged petiole; outer involucral scales very large; rays 10–15, linear-oblong, much longer than the inner scales of the involucre, yellow; achenes strongly striate.—Rich soil, W. New York and N. J. to Mo., and southward.
37. SÍLPHIUM, L. Rosin-weed.
Heads many-flowered, radiate; rays numerous, pistillate and fertile, their broad flat ovaries imbricated in 2 or 3 rows; disk-flowers apparently perfect, but with entire style and sterile. Scales of the broad and flattish involucre imbricated in several rows, thickish, broad and with loose leaf-like summits, except the innermost, which resemble the linear chaff of the flat receptacle. Achenes broad and flat, dorsally compressed, surrounded by a wing notched at the top, without pappus, or with 2 teeth confluent with the winged margin, the achene and its subtending chaff usually falling together; those of the disk sterile and stalk-like.—Coarse and tall rough perennial herbs, with copious resinous juice, and large corymbose-panicled, yellow-flowered heads. (Σίλφιον, the ancient name of some resinous plant, transferred by Linnæus to this American genus.)
[*] Stem terete, alternate-leaved (root very large and thick).
1. S. laciniàtum, L. (Rosin-weed. Compass-Plant.) Rough-bristly throughout, stem stout (3–12° high), leafy; leaves pinnately parted, petioled but dilated and clasping at the base; their divisions lanceolate or linear, acute, cut-lobed or pinnatifid, rarely entire; heads few (1–2´ broad), sessile or short-peduncled along the naked summit; scales ovate, tapering into long and spreading rigid points; achenes broadly winged and deeply notched, 6´´ long.—Prairies, Mich. to Dak., and southward. July.—Lower and root-leaves vertical, 12–30´ long, ovate in outline; on the wide open prairies disposed to present their edges north and south; hence called Compass-Plant.
2. S. terebinthinàceum, L. (Prairie Dock.) Stem smooth, slender (4–10° high), panicled at the summit and bearing several or many, large heads, leafless except toward the base; leaves ovate and ovate-oblong, somewhat heart-shaped, serrate-toothed, thick, rough, especially beneath (1–2° long, on slender petioles); scales roundish, obtuse, smooth; achenes narrowly winged, slightly notched and 2-toothed.—Var. pinnatífidum, Gray, has the leaves deeply cut or pinnatifid, but varies into the ordinary form.—Prairies and oak-openings, Ohio and Mich. to Minn., and southward. July–Sept.
[*][*] Stem terete or slightly 4-angled, leafy; leaves undivided (not large), some opposite.