104 POLYGONACEAE (BUCKWHEAT FAMILY) 
Means of control 
Prevent seed development. Even so expensive a process as 
hand-pulling is often worth the labor if it hinders so pernicious a 
weed as this from fouling the ground with its long-lived seeds. In 
grasslands and grain fields a spray of four-per-cent solution of 
Copper sulfate will greatly damage the foliage of the weed, checking 
growth and usually blasting the budding flowers. In cultivated 
ground it is readily subdued by the necessary tillage. 
BLACK BINDWEED 
Polygonum Convéloulus, L. 
Other English names: Wild Buckwheat, Knot Bindweed. 
Introduced. Annual. Propagates by seeds. 
Time of bloom: June to September. 
Seed-time: July until cut off by frost. 
Range: Throughout North America ex- 
cept the extreme North. 
Habitat: Fields and waste places; invades 
most crops. 
Not very troublesome in ground re- 
quiring close tillage, but a special nuisance 
in grain fields ; climbing over and strangling 
the rightful growth, robbing it of food 
and moisture, bending it down by weight 
of its own fruitage. The seeds have long 
vitality and begin to ripen and drop into 
the soil before harvest; are gathered with 
the grain and often distributed with it; 
often fed to cattle in screenings from the 
mills, and returned to the soil in stable 
refuse or in droppings. : 
Stem slightly angular, roughish, branch- 
ing, one to three feet long. Leaves 
halberd-shaped or long-pointed, heart- 
. shaped, smooth, dark green, with slender 
a ai feces oa petioles usually not so long as the blades. 
volvulus). X}. Flowers in slim, interrupted, axillary ra- 
