STUDIES IN THE COMPOSIT E. 261 
long (only the upper cauline known), sessile, not connate: 
heads solitary in the forks or peduncles 4 to 8 inches long, 
these naked, or with a pair of leaves below the middle: 
outer involuere of oblong-linear obtuse serrulate bracts of 
twice or thrice the length of the broad low-hemispherical 
head: rays 5 to 8, small for the head and inconspicuous, 
deep-yellow fading whitish: disk-corollas very short, the 
tube and limb of about equal length: achenes also very 
short, narrow-turbinate, 4-angled and 4-awned, less com- 
pressed than in related species, the angles somewhat suber- 
ous-thickened, tubereulate under the retrorse hairs; awns 
stout, of about half the length of the achene, more rigidly 
aculeolate. 
In ditches at Brandon, Manitoba, 29 July, 1896, John 
Macoun, n. 12,180. A plant which, at first view, by its 
broad low head and small rays, suggested the north Euro- 
pean B. platycephala, and I became suspicious of that as pos- 
sibly introduced into Manitoba; but the further observation 
that the specimens in hand were mere branches of what 
must be a very large and rank ditch weed, and of remark- 
ably dichotomous branching, removed allsuch apprehension. 
V B. RIPARIA. Low, simple or sparingly branched, only 4 
to 6 inches high, the stems glabrous, striate: leaves lanceo- 
late, 13 to 21 inches long, remotely appressed-serrate: heads 
large for the plant, campanulate: outer involucre foliaceous, 
far surpassing the inner and the flowers, the bracts ellipti- 
cal, spinulose-serrate: rays none; disk-corollas minute, the 
slender tube and short-cylindric or subclavate limb of equal 
length, the latter 4-toothed, greenish-yellow, marked for its 
whole length with 4 black lines: achenes cuneate, com- 
pressed-trigonous, the two margins cartilaginous-thickened 
and retrorsely but remotely hispid, the two longer and 
