POLYGONACEAE (BUCKWHEAT FAMILY) 101 
fungus which turns the heads into a mass of purple spores, de- 
stroying the fruits so that “purplehead”’ is a benefit from the 
farmer’s point of view. Achenes black, lens-shaped, smooth, and 
shining. (Fig. 59.) 
Means of control 
Cut closely or pull before any seeds have matured. Rankly 
infested ground should be put under cultivation before being again 
used for clover or grass. Good drainage is an assistance in subdu- 
ing this weed, for it likes the soil to be moist. 
COMMON SMARTWEED 
Polygonum Hydrépiper, L. 
Other English names: Water-pepper, 
Biting Knotweed. 
Native. Annual. Propagates by seeds. 
Time of bloom: June to September. 
Seed-time: July to November. 
Range: Throughout North America. 
Naturalized in the Eastern States, but 
indigenous in the Northwest. : 
Habitat: Low fields and meadows; gar- 
dens and barnyards, waste places. 
The juice of this plant is exceedingly 
biting and pungent to the taste and 
will raise blisters when applied to the 
skin. It is not insistently a water- 
weed, as its name implies, but will grow 
where the soil is only moderately moist. 
Stem smooth, erect, slender, with few 
branches, ten inches to two feet tall, 
light green or frequently of a reddish 
color. Leaves narrow lance-shaped, one 
to four inches long, with short petioles, 
the surface dotted with glands, the edges 
entire or slightly wavy, ciliate, the Gs ag eommennae 
sheathing stipules cylindric and fringed weed (Polygonum Hydropiper). 
with short bristles. Flowers in slender, %?- 
