1910} Hill,— Pasture-Thistles; east and west 213 
fact too often escapes attention, it obviously being more convenient 
in collecting the plant to cut it off rather than to dig it up entire. 
The specimens of thistle at Saegertown had a tap root, more or less 
branching or with smaller side roots, the main root tapering down- 
ward as properly in a tap root. The roots of C. Hilli are fusiform, 
usually hollow, and connected by.a narrow neck-like part with the 
base of the stem. Sometimes several spring from the base forming an 
imperfect fascicle, each connected with the stem by a slender neck. 
I have found as many as five of these to a single stem. An individual 
with three is figured in the proceedings of the Davenport Academy of 
Sciences, 8: 287, Pl. 2, 1900. When single the root is generally per- 
pendicular and runs deeply down, so that it is difficult if not impos- 
sible to pull it up, since the narrower neck almost invariably breaks 
off leaving the most characteristie portion in the ground. The plant 
being a perennial these several stems may be the product of different 
years, one of them being commonly longer and larger than the rest. 
As the bud for a succeeding year’s growth forms a little beneath the 
surface, it would be advantageous to send down a new subterranean 
part to aid in perpetuating the plant. 
Though the flowers of C. Hillii are normally of a deep shade of 
pink-purple, they sometimes take on a brighter shade of red or be- 
come red-purple, or magenta-like. In such cases a large head two or 
three inches across becomes very ornamental in character. The 
bracts of the involucre in this western thistle are very glutinous on 
account of a dark gland near the tip. But I found on the bracts of 
the pasture thistle (C. pumilum) at Saegertown a more glutinous line 
than might be inferred from the common descriptions, the bracts 
being sticky enough to adhere with considerable force to the drying 
papers and tear off bits of the latter when removed. 
The habitat of C. Hillii is a dryish soil. It comes under Warming’s 
classification of mesophytie plants, an inhabitant of prairies, meadows 
and pastures, but with a tendency towards the drier extreme. My 
first collection of the plant, near the Kankakee river at Waldron, Ill., 
June, 1870, is labelled as from “dry fields." It was then confounded 
with C. pumilum, as our only pasture thistle. So too at first in the 
sand region east of Chicago where its distinctness was subsequently 
observed. It was on the low sand ridges that run somewhat parallel 
with one another on the old lake bottom, raised but a few feet above 
adjoining sloughs or ponds, only slightly above the present level of 
