THE KNOTWEED FAMILY 



POLYGONACEiE LINDLEY 



OSTLY composed of herbaceous plants in the temperate zones, this 

 large family, which includes over 30 genera and nearly 1000 species, 

 contains a considerable number of trees and shrubs in tropical regions. 

 The leaves are simple, mostly entire-margined, usually alternate, rarely 

 opposite or whorled, and have characteristic sheathing united stipules (called 

 ochreae). The small regular flowers are variously clustered; the calyx is free from 

 the ovar}', lobed, or composed of separate sepals; there are no petals; there are 

 from 2 to 9 stamens with slender filaments and 2-celled anthers; there is but one 

 pistil, the I -celled ovary containing i ovule and tipped by a 2-cleft or 3-cleft style. 

 The fruit is an achene, usually invested or enclosed by the persistent calyx, which 

 in the following genus becomes fleshy, so that the fruit often resembles a berry or 

 grape. 



This family yields a few valuable products. Among foods. Buckwheat, the 

 seed of Fagopyrum Fagopyrum (Linnaeus) Karsten, also produced by other species 

 of Asiatic origin, is the most important. The popular Pie plant, or Rhubarb, is 

 the leaf-stalk of Rheum Rhaponticum Linnaeus, the root of which is also used as a 

 purgative, but is very inferior to the official Rhubarb, which is the root of the Asi- 

 atic Rheum officinale Baillon. The roots and herbage of several species of the 

 genus of well-known weeds. Polygonum, often called Smartweeds or Water peppers, 

 are sparingly used in medicine ; the roots of several species of Rumex, Docks, are 

 employed as astringents ; the root of Rumex hymenosepalus Torrey, called Canaigre 

 is used in tanning; it is native of the southwestern States and Mexico. 



I. THE GRAPE TREES 



GENUS COCCOLOBIS PATRICK BROWNE 



OME 120 kinds of Grape trees are known, all natives of warm and 

 tropical America, many occurring in the West Indies, two of which 

 grow naturally also in southern Florida. Some of the species are 

 low shrubs, but a number form tall trees, while a few are woody 

 vines; all have simple evergreen, entire-margined leaves, with the characteristic 

 stipular sheaths (ochreae) of the family. The perfect small flowers are clustered in 

 racemes and borne on short pedicels, which are jointed beneath the 5-lobed calyx; 

 there are 8 stamens with rather slender filaments, borne at the top of the calyx- 



378 



