POLYGONEiE. 101 



ORDER 156. POLYGONEiE. The Buckwheat Tribe. 



Calix inferior, divided, sometimes colored so as to resemble a 

 corolla, bearing the stamens at its base ; nut naked or covered by 

 the calyx, commonly triangular ; seed generally farinaceous ; 

 leaves alternate, with stipules round the outside of the petioles ; 

 flowers sometimes only bearing stamens or pistils, often in ra- 

 cemes and beautiful, often coarse and unsightly. 



Polygonum. L. 8. 3. 

 Named from the Greek, many knees or joints, from the form of 

 the stem. About 70 species have been described, most of which 

 are natives of Europe, and the north part of Asia ; 24 species 

 are credited by Nuttall to North America ; and 17 species are 

 found in this State, some of which have been introduced from the 

 other side of the Atlantic. Some follow man, and make their 

 home around his dwelling. 



P. aviculare. L. Knotgrass. Forming a thick carpet about 

 houses, and by its seeds supporting small birds, whence its spe- 

 cific name. Although unlike the grasses, yet, because its stem is 

 jointed or knotted, and it is eaten by cattle, it is called Knot- 

 grass. 



P. persicaria. L. Heartease, or Heartspot. About gar- 

 dens and fields, with a dark and rather heart-shaped spot on most 

 of the leaves. 



P. punctatum. Ell. Water-pepper. In moist places, and 

 about rubbish ; it is only a variety, and ought so to be named, 

 of P. hydropiper, L. ; it yields a yellow dye, and is strongly 

 diuretic. 



P. hydropiperoides. Mx. Occasionally found about Boston. 

 Big. 



P. sagittatum. L. Prickly or Arrow-shaped Knotweed. 



