1^8 CLASS VIII. ORDER III. 



expanding of the lower flowers first, at length cylindrical. Flow- 

 ers rose colored. — In deep waters. — August. — Perennial, 

 Polygonum articulatum. L. Jointed Polygonum. 



Stamens ciglit, styles three; spikes panicled, fili- 

 form; flowers solitary, pedunculated; bractes imbri- 

 cate, truncate ; leaves linear. 



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

 slender, branching, with truncated sheathes. Leaves small, 

 linear. The spikes are jointed by a succession of imbricate 

 sheathing bractes, from eac'i of which proceeds a capillary, nod- 

 ding peduncle, bearing a handsome, reddish white flower. — Dry 

 hills and pastures. — August. — Annual. 



Polygonum sagittatum. L. Scratch Grass. 



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-sliaped, oblong, on short petioles, 

 the petiole and mid rib rougli backward. Flowers in small heads 

 on the ends of the branches, white or purplish. — Wet ground. — 

 July. — 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 sep- 

 arate, pale, reddish flowers. — Found in a marshy spot near Mount 

 Auburn, Cambridge. — June, July. — Annual. 

 Polygonum convolvulus. L. Black Bindweed. 



Leaves heart-arrow shaped ; stem twining angular; 

 segments of the calyx bluntly keeled. Sni. 



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 



