POLTGONACEAE (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 Hydropiper, 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 FlG . 60 ._ CommonSmart . 

 sheathing stipules cylmdric and fringed wee d (Polygonum Hydropiper). 

 with short bristles. Flowers in slender, x i. 



