158 Buckwheat ( Polygonhcece). [No. 22 



(2) Arrow-leaved Tear-Thumb (P. sagittatum, L.). 

 (a) Stems not prickly. 



(6) Sheaths naked. Fruit not winged. 



(3) Black Bindweed (P. convolvulus, L.). 

 (6) Sheaths fringed at base. Fruit not winged. 



(4) Bristly-jointed Bindweed (P. cilinode, Mx.). 

 (6) Sheaths not fringed. Fruit winged. 



(5) Hedge Bindweed (S. scandens, L.). 



Fig, 74. — (1) Halberd-Leaved Tear-Thumb. P. arifblium, L. 



Flowers, small, white or pale rose, in few-blossomed spikes. 

 Calyx, often four-parted. Stamens, six. Styles, two, 

 very short. June to October. 



Leaves, two to four inches in length, halberd-shaped, the 

 base a pair of spreading pointed lobes, the apex taper- 

 ing and pointed. Leaf-stem, one half to one inch in 

 length, roughened with downward-pointing prickles. 



Fruit, large, flattened, the shape of a double convex 



lens. 

 Found, in low and wet ground from Canada to Georgia 



and westward. 



A weak vine, two to three feet long, climbing by help of 

 fine downward-pointing prickles on the edges of its 

 grooved and often red stem. 



Fig- 75- — ( 2 ) Arrow-Leaved Tear-Thumb. Scratch-Grass. 



P. sagittatum, L. 



Flowers, whitish or pale rose, in small heads. Stamens, 

 usually eight. Styles, three, slender. Cluster-stems, 

 smooth and usually reddish or nearly white. June to 

 October. 



Leaves, one to three inches in length, arrow-shape. Leaf- 

 stem, short, sheathing stipules at the joints, smooth, 

 membranaceous. 



