IOWA ACADEMY OF SCIENCES. 
225 
heads, with whitish, purple or reddish, usually perfect, 
rarely dioecious flowers; receptacle flat or somewhat con- 
vex, bristly. Corolla with a long tube deeply regularily or 
unequally cleft, stamens with acute anther tips, sagittate 
at base, filaments usually pubescent, occasionally hairy; 
style branching, short, with appendage united nearly up to 
the obtuse tips, with a hairy ring near the tip, bristles of 
the pappus connate at the base, usually soft plumose, 
occasionally bristles of outer flowers barbellate; the tips 
clavate, achenes oblong, obovate compressed, striated, or 
obtusely 4-angled, glabrous. 
In the recent revision of the order it has been customary 
to place Cnicus in with Carduus on the basis of the charac- 
ters found in the pappus, the pappus of Carduus being 
merely barbellate. Cirsium is retained by Hoffmann in 
Engler and Prantl. Pflanzenfamilien. In recent studies of 
many species the writer has found merely barbellate 
bristles of the outer flowers, but the subtending leaf-like 
bracts under the involucre is a further distinguishing fea- 
ture. The inner bracts have more or less bristly append- 
ages in some of the western species, and in this respect 
approaches Centaur ea, although in this genus the pappus 
consists of aristiform bristles, fimbriolate or of narrow 
palese. It seems to me that these genera should be 
retained. 
Twenty-two species are recorded for oriental Asia by 
Maximowicz;* and forty-three species for North America, 
north of New Mexico.f 
According to Bentham and Hooker something like 200 
species are described, chiefly temperate Europe and Asia 
and northern Africa and North America, but the number 
of species has increased somewhat, since the publication of 
the genera plantarum in 1878. The estimated number 
now being 250. The total number listed by Heller is 
seventy-three, whereas in Patterson’s check list there are 
forty-three. It will be seen, therefore, that more than 
half of the increase in the number of species must be 
* Bull. Acad. Petersb. 19 : 489. Mel. Biol. 9 : 301. 
f Gray. Syn. FI. N. Am. 1 : 398. 
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