CRUCIFERAE (MUSTARD FAMILY) 193 
Kansas, northwestward to Washington; all the Canadian prov- 
inces from Quebec to Vancouver Island. 
Habitat: Grain fields and grasslands, waste places. 
A native of Central Europe brought to this country in impure 
commercial seeds ; by this agency it still travels, and no doubt jour- 
neys farther in this way than when wind-driven about the country. 
Stem two to four feet high, slender, smooth, and exceedingly 
branched and bushy. Leaves 
deeply pinnatifid, the segments 
nearly linear, toothed or entire, 
the upper ones reduced to 
thread-like thinness; when the 
plant is young the lower leaves 
are downy and the basal ones lie 
on the ground in rosette form, 
but, these wither away and the 
laterleaves are smooth. Flowers 
pale yellow, about a third of an 
inch across, on elongating ra- 
cemes that leave behind alter- 
nating rows of stiff, diverging, 
needle-like pods, two to four 
inches long but hardly thicker 
than their short pedicels. Each 
pod usually contains more than 
a hundred seeds — the fecundity 
of the weed is almost incredible. : ; 
When mature the stems become *™ so iris ae, as sana 
very brittle, breaking away at 
the surface of the ground, and the plants are afterward the sport 
of the winds; on the prairies they often roll for miles, but in 
fenced and uneven ground they are battered to and fro, seeding 
the soil the more thickly for such restriction. (Fig. 136.) 
Means of control 
Sow clean seed. Harrow seedlings out of grain fields in the spring. 
Harvest infested meadows before the first seeds ripen. Burn over 
° 
