102 PLANTS OF MASSACHUSETTS. 



Grows in wet places, with arrow-shaped leaves, and an exceed- 

 ingly rough stem, with teeth backwards. 



P. arifolium. L. Has a stem like the other, but larger and 

 stouter, and with much larger leaves, less distinctly sagittate, and 

 more halberd-shaped ; grows in wet places, and is often associated 

 with P. Pennsylvanicwn, L., from which it is clearly separated, 

 and yet resembles it. 



P. coccineum. Willd. Purple Knotweed. Named from the 

 color of both the leaves and the dense spikes of flowers ; grows on 

 the edges of ponds, with its long, smooth leaves, gracefully float- 

 ing, greenish above, and purple or reddish below ; common about 

 the ponds of Berkshire County, and also in the vicinity of Bos- 

 ton ; blossoms in July. 



P. amphibium. L. Grows more out of the water than the 

 last, and is eradicated with much difficulty from recovered lands. 



P. convolvulus. L. Bindweed or Bind-Knotweed. Alter- 

 nate and heart-shaped leaves ; grows as a twining vine round 

 other plants ; abundant in cultivated fields ; flowers unsightly. 



P. cilinode. Mx. Climbing Bindweed. Less common than 

 the other, with deep, heart-shaped leaves, and climbing on and 

 over other plants. 



P. scandens. L. Resembles Buckwheat in its flower and 

 fruit, but climbs like the other. 



Some other species, P. articulatum, L., lapathifolium, L., 

 mite, Pers., tenue, Mx., and Virginianum, L., are of still less 

 consequence. 



P. fagopyrum. L. Buckwheat, or properly Beechwheat. 

 So called from the close resemblance of its seeds to the seed of 

 the Beech tree, or Fagus ; a native of Asia, partially naturahzed 

 in England and this country. The lateness of the season for 

 sowing this seed, viz. about July 4th, its rather prolific character, 



