458 COMPOSITAE (COMPOSITE FAMILY) 
brine — the soil being cleaned of all plant-growth for a season 
rather than allow the pest to gain a foothold. Large areas can 
be finally suppressed by putting the ground under cultivation, 
plowing deeply during very dry weather, and exposing the root- 
stocks as much as possible; after this summer fallowing put in a 
hoed crop, and give such persistent and careful tillage as to kill 
surviving rootstocks by depriving them of leaf growth. 
WHITE-LEAVED FRANSERIA 
Pranstria discolor, Nutt.) 
(Gaertnéria discolor, Kuntze.) 
Other English names: Bur Ragweed, Creeping Ragweed. 
Native. Perennial. Propagates by seeds and by rootstocks. 
Time of bloom: July to September. 
Séed-time: September to November. 
Range: The Plains region west of the Missouri River, to Wyoming, 
Colorado, and New Mexico. 
: Habitat: Dry soil; prairies; meadows 
and pastures, cultivated fields, waste 
places. 
A near relative of the Common Rag- 
weed, but much more pernicious be- 
cause of its creeping rootstocks. Stems 
twelve to eighteen inches tall, much 
branched, and spreading, hoary with 
white hairs. Leaves alternate, smooth 
and green above but densely white- 
woolly beneath, coarsely toothed, long 
and bipinnate, the lobes narrow and 
very irregular, separated by narrow, 
winged segments, the petiole similarly 
winged. Flowers of two kinds, the 
sterile ones in narrow terminal racemes, 
the heads, about one-sixth of an inch 
long, on very short pedicels; the fertile 
heads in the axils below, singly or in 
_ Fic. 320. — White-leaved i 
Franseria (Franseria discolor). SMall clusters; the involucre forms a 
Xt. tiny bur, about a sixth of an inch long, 
