158 Class VIII. Order III. 



form ; flowers solitary, pedunculated ; bractes imbri- 

 cate, truncate ; leaves linear. 



A delicate, erect species with numerous spikes. Stem straight, 

 slender, branching, with truncated sheaths. Leaves small, linear. 

 The spikes are jointed by a succession of imbricate sheathing 

 bractes, from each of which proceeds a capillary, nodding pe- 

 duncle, bearing a handsome, reddish white flower. Dry hills 

 and pastures. August. Annual. 



POLYGONUM SAGITTATUM. L. Scratch GrttSS. 



Stem prickly backward ; leaves sagittate ; flowers 

 in heads, with eight stamens and three styles. Mich. 



Stem slender, four angled, the angles rough backward with 

 small prickles. Leaves arrow-shaped, oblong, on short petioles, 

 the petiole and mid rib rough backward. Flowers in small 

 heads on the ends of the branches, white or purplish. Wet 

 ground. J uly. Annual. 



POLYGONUM ARIFOLIUM. L. Hastate Polygonum. 



Stem prickly backward ; leaves hastate ; spikes 

 few flowered, flowers distinct, with six stamens and 

 two styles. Mich. 



Stem as in the last. Leaves halberd-shaped, twice as > large 

 as the last, thin and tender. The stem terminates with a few 

 separate, pale, reddish flowers. Found in a marshy spot near 

 Sweet Auburn, Cambridge. June, July. Annual. 



POLYGONUM CONVOLVULUS. L. Black Bindweed. 



Leaves heart-arrow shaped ; stem twining, angu- 

 lar ; segments of the calyx bluntly keeled. Sm. 



Stem twining, climbing on other plants. Leaves alternate, 

 petioled, heart-shaped, with the hinder lobes acute. Branches 

 axillary. Flowers in terminal, interrupted spikes whitish, the 

 three principal segments of the calyx furnished with a keel, but 

 not winged. Flowers all summer in waste and cultivated ground. 



O '' 



Annual. 



