COMPOSITE. (COMPOSITE FAMILY.) 273 



67. CIRSIUM, Tourn. Common or Plumed Thistle. 



Heads many-flowered ; the flowers all tubular, perfect and similar, or rarely 

 imperfectly dioecious. Scales of the ovoid or spherical involucre imbricated in 

 many rows, tipped with a point or prickle. Keceptacle thickly clothed with soft 

 bristles or hairs. Achenia oblong, flattish, not ribbed. Pappus of numerous 

 bristles united into a ring at the base, plumose to the middle, deciduous. — Herbs, 

 with sessile alternate leaves, often pinnatifid, and prickly. Heads large, ter- 

 minal. Flowers reddish-purple, occasionally yellowish, white, or cream-color; 

 in summer. (Name from Kipaos, a swelled vein, for which the Thistle was a 

 reputed remedy.) 



* Sades of the involucre all tipped with spreading prickles : root biennial. 



1. C. laxceolatum, Scop. (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. — Pastures 

 and roadsides, everywhere, at the North. (Nat. from Eu.) 



* * Scales of the involucre oppressed ; the inner ones not prickly : filaments hairy. 



•*- Leaves white-woolly beneath, and sometimes also above: outer scales of the involucre 



successively shorter, and tipped with short prickles. 



2. C. Pitcheri, Torr. & Gr. White-woolly throughout, perennial, low ; stem 

 stout, very leafy ; leaves all pinnately parted into rigid narrowly linear and elongated 

 divisions, with revolute margins; flowers cream-color. — Sandy shores of Lakes 

 Michigan, Huron, and Superior. 



3. C. Ulldulatum, Spreng. White-ivoolly throughout, biennial, low and 

 stout, leafy; leaves lanceolate-oblong, partly clasping, nndulate-pinnatifid, with 

 prickly lobes ; flowers reddish-purple. — Islands of L. Hurou and Michigan ; 

 thence westward. 



4. C. discolor, Spreng. Biennial; stem grooved, hairy, branched, tall, 

 leafy; Jeaves all deeply pinnatifid, sparingly hairy and green above, whitened with 

 close wool beneath; the diverging lobes 2-3-cleft, linear-lanceolate, prickly-pointed; 

 flowers pale purple, rarely white. — Meadows and copses. 



5. C. altissimum, Spreng. Stemdowny, branching (3° -10° high), leafy 

 quite to the heads: leaves roughish-hairy above, whitened with close wool beneath, 

 oblong-lanceolate sinuate-toothed, undulate-pinnatifid, or undivided, the lobes or teeth 

 prickly ; those from the base pinnatifid ; and their lobes short, oblong or triangular: 

 flowers chiefly purple. — Fields and copses, Penn. to Illinois and southward. 



6. C. Virginianum, Michx. Stem woolly, slender, simple or sparingly 

 branched (l°-3° high) ; the branches or long peduncles naked: leaves lanceolate, 

 green above, whitened with close wool beneath, ciliate with prickly bristles, en- 

 tire or sparingly sinuate-lobed, sometimes the lower deeply sinuate-pinnatifid ; outer 

 scales of the involucre scarcely prickly ; heads small ; flowers purple. — Woods 

 and plains, Virginia, Ohio, and southward. 



Var. filipendulu.nl. Stem stouter, more leafy, corymbosely branched 

 above ; the heads on shorter peduncles ; leaves pinnatifid ; roots tuberous, en- 

 larged below. (C. filipendulum, Engelm.) — Prairies of S. Illinois and south- 

 westward. 



18 



