160 Buckwheat ( Polygonacece). [No. 22 



Fruit, sharply three-angled. Achene, nearly black, smooth, 

 nearly as broad as long. 



Found, common everywhere in low ground. 



A slender, usually prostrate vine, not twining, two to 

 five feet in length ; mostly smooth, excepting on the edges 

 of the four-angled stem, and on the mid-vein of the leaf 

 and leaf-stem. These parts are set with fine and very 

 sharp downward-pointing prickles. 



Fig. 76.— (3) Black Bindweed. Knot Bindweed. [P. con- 



vdlvulus, Z.] 



Flowers, whitish, either sessile or in small loose clusters 

 from the axils of the leaves. Calyx, five-lobed, twice 

 as long as the flower-stem, the three outer lobes 

 keeled. Stamens, eight. Styles, three, very short. 

 July and August. 



Leaves, one to two inches or more in length, halberd-heart- 

 shape, tapering to the apex, with usually pointed and 

 somewhat spreading lobes at the base. Sheathing- 

 stipules, not fringed at their base as in No. 4 (Bristly- 

 Jointed Bindweed). 



Fruit, three-angled, not winged around as in No. 5 

 (Hedge Bindweed). Achene, dull black, under the 

 lens roughish (striate), the sides ovate-triangular to 

 oval. 



Found, common in cultivation and in waste ground 

 from Canada to North Carolina. Naturalized from 

 Europe. 



A prostrate or climbing and twining vine, with a ridged, 

 roughish, but not prickly stem, two to three feet in 

 length. 



