552 COMPOSITAE (COMPOSITE FAMILY) 
in each head; involucre cylindric, 
with eight to ten linear bracts in its 
principal row, with a few short, 
spreading outer ones. Achenes 
small, slender, with fine, straw-col- 
ored pappus. 
Means of control 
Cut flower-stalks close to the 
ground before the buds unfold, thus 
preventing seed development and 
distribution. Drainage and cultiva- 
tion of the soil are necessary in order 
to kill the perennial roots. 
ROUGH WHITE LETTUCE é 
Prendnthes dspera, Michx. 
(Ndbalus dsper, T. & G.) 
TBiiyy Perennial. Propagates by 
seed. ; 
aie of bloom: August to Septem- 
er. 
Vi, Seed-time: September to October. 
od? Range: Ohio to South Dakota, south-- 
Fie, 382. — Smooth White oe aa a and 
: ouisiana. 
ae EGGS” SBtenioee)s Habitat: Dry prairies; fields, pas- 
tures, waste places. 
Grazing cattle usually leave this weed undisturbed to perfect 
its fruit, liking neither its rough-hairy foliage nor its bitter juices. 
Stem stout, simple, ridged, and bristly-hairy, two to four feet tall. 
Leaves long-oval or broadly Jance-shaped, rather thick and firm, 
rough on both sides, sparsely toothed, obtuse, the basal ones taper- 
ing to winged petioles; those on the stem all sessile, the lower ones 
clasping and obtuse, the uppermost usually entire and acute. 
Heads numerous, in a long, spike-like panicle, mostly erect on very 
short ‘pedicels, each about a half-inch broad, with twelve to fifteen 
cream-colored florets ; involucre cylindric, very hairy, its principal 
