244 COMPOSITE. (composite family.) 
somewhat hairy , pinnatifid, icith short and cut very prickly-margined 
lobes ; outer scales of the involucre prickly-pointed , the inner very 
slender; flowers purple or rarely white. © — Low or dry fields, 
Maine to Penn., near the coast. July. — Stem l°-3?high: heads 
14 ' broad; the fragrant flowers 2' long. 
9. C. horrid ilium, Michx. (Great Yellow Thistle.) 
Stem stout , webby-haired when young; leaves partly clasping, green, 
soon smooth, lanceolate, pinnatifid , the short toothed and cut lobes very 
spiny with yellowish prickles ; heads large, surrounded at the base by 
an involucrate whorl of leaf-like and very prickly bracts , which equal 
or exceed the narrow and unarmed scales of the involucre ; flowers 
pale yellow, often turning purple in fading. — Sandy fields, &c., Mas¬ 
sachusetts to Penn, and southward, near the coast. June-Aug.— 
Plant 1° -4° high: the heads nearly as large as in the last. 
* * * Outer scales of the oppressed involucre barely prickly-pointed: 
filaments nearly smooth : heads imperfectly dioecious. 
10. C. arvense, Scop. (Canada Thistle.) Low, branched; 
roots extensively creeping; leaves oblong or lanceolate, smooth, or 
slightly woolly beneath, sinuate-pinnatifid, prickly-margined; heads 
small and numerous; flowers rose-purple 1|. — Cultivated fields and 
pastures, naturalized: a most troublesome weed, which it is extreme¬ 
ly difficult to eradicate. July, Aug. 
56. ONOPORDON, Vaill. Cotton Thistle. 
Heads and flowers nearly as in Cirsium. Scales of the involu¬ 
cre coriaceous, tipped with a lanceolate prickly appendage. Re¬ 
ceptacle deeply alveolate. Achenia 4-angled, wrinkled trans¬ 
versely. Bristles of the pappus numerous, slender, not plumose, 
united at the base into a horny ring. — Coarse branching herbs, 
with the stems winged by the decurrent base of the lobed and 
toothed somewhat prickly leaves. Heads large : flowers purple. 
1. O. ac&nthium, L. Stem and leaves woolly; scales of 
the involucre linear-awl-shaped. ©-Road-sides, naturalized m 
New England. July. - A tall cottony plant. 
5 7. LAPPA, Toum. Burdock. 
Heads many-flowered, the flowers all perfect and similar. I°" 
volucre globose; the imbricated scales coriaceous and appressed at 
the base, produced into an abrupt and spreading awl-shaped ap¬ 
pendage, with a rigid hooked point. Receptacle bristly. Achema 
oblong, flattened, wrinkled transversely. Pappus short, of numer¬ 
ous rough bristles, not united at the base, deciduous. — Coarse bi- 
