78. ÁRCTIUM, L. Burdock.
Heads many-flowered; flowers all tubular, perfect and similar. Involucre globular; the imbricated scales coriaceous and appressed at base, attenuate to long stiff points with hooked tips. Receptacle bristly. Achenes oblong, flattened, wrinkled transversely; pappus short, of numerous rough bristles, separate and deciduous.—Coarse biennial weeds, with large unarmed and petioled leaves, and small solitary or clustered heads; flowers purple, rarely white. (Name probably from ἄρκτος, a bear, from the rough involucre.)
A. Láppa, L. Stout, 1–3° high; leaves roundish or ovate and mostly cordate, or lanceolate with cuneate base, smooth above, somewhat floccose-tomentose beneath, mostly sinuate-denticulate. (Lappa officinalis, All.)—The several reputed species of the genus are scarcely distinguishable even as varieties. Var. mìnus, has rather small ovoid subracemose heads (about 8´´ broad), on short peduncles, glabrous or somewhat cottony, the inner scales somewhat purplish-tipped, equalling the flowers; leaves occasionally cut-toothed. By roadsides; very common.—Var. màjus, with broader (1´) green and glabrous subcorymbose rather long-pedunculate heads. Less frequent.—Var. tomentòsum, a form of the last with more spherical webbed heads, with purplish scales shorter than the flowers. Rare.—July–Oct. (Nat. from Eu.)
79. CNÌCUS, Tourn. Common or Plumed Thistle.
Heads many-flowered; flowers all tubular, perfect and similar, rarely imperfectly diœcious. Scales of the ovoid or spherical involucre imbricated in many rows, tipped with a point or prickle. Receptacle thickly clothed with soft bristles or hairs. Achenes oblong, flattish, not ribbed; pappus of numerous bristles united into a ring at the base, plumose to the middle, deciduous.—Herbs, mostly biennial, with sessile alternate leaves, often pinnatifid, prickly. Heads usually large, terminal. Flowers reddish-purple, rarely white or yellowish; in summer. (Latin name of the Safflower, from the Greek κνῆκος.)
[*] Scales of the involucre all tipped with spreading prickles.
C. lanceolàtus, Hoffm. (Common Thistle.) Leaves decurrent on the stem, forming prickly lobed wings, pinnatifid, rough and bristly above, woolly with deciduous webby hairs beneath, prickly; flowers purple. (Cirsium, Scop.)—Pastures and roadsides, everywhere, at the North. (Nat. from Eu.)
[*][*] Heads leafy-bracteate at base (see also n. 8); proper scales not prickly.
1. C. horrídulus, Pursh. (Yellow Thistle.) Stem stout (1–3° high), webby-haired when young; leaves partly clasping, green, soon smooth, lanceolate, pinnatifid, the short toothed and cut lobes very spiny with yellowish prickles; heads (1–1½´ broad) surrounded by leaf-like and very prickly bracts, which usually equal the narrow scales; flowers pale yellow or purple. (Cirsium, Michx.)—Sandy fields, Mass. to Va., and southward, near the coast.
[*][*][*] Scales appressed, the inner not at all prickly.