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._ [+] _Leaves white-woolly beneath, and sometimes also above; outer scales successively shorter, and tipped with short prickles._ 2. C. Pítcheri, Torr. _White-woolly throughout_, low; stem very leafy; _leaves all pinnately parted into rigid narrowly linear and elongated, sometimes again pinnatifid divisions_, with revolute margins; flowers cream-color. (Cirsium, _Torr. & Gray_.)--Sandy shores of Lakes Michigan, Huron, and Superior. 3. C. undulàtus, Gray. _White-woolly throughout_, low and stout, leafy; _leaves lanceolate-oblong_, partly clasping, undivided, _undulate-pinnatifid_, or rarely pinnately parted, moderately prickly; flowers reddish-purple. (Cirsium, _Spreng._)--Islands of L. Huron to Minn., Kan., and westward. The heads vary much in size. 4. C. altíssimus, Willd. Stem downy, branching (3--10° high), _leafy quite to the heads; leaves_ roughish-hairy above, whitened with close wool beneath, _oblong-ovate to narrowly lanceolate, undivided, sinuate-toothed, undulate-pinnatifid, or twice pinnatifid_, the lobes or teeth weakly prickly; heads 1½--2´ high; flowers chiefly purple. (Cirsium, _Spreng._)--Fields and copses, Mass. to Minn., and southward. Var. discolor, Gray. Stem 2--6° high; leaves nearly all deeply pinnatifid into lanceolate or linear lobes. (Cirsium discolor, _Spreng._)--Common; N. Eng. to Ill., and southward.