538 POLYGONACE^E. 



by ants, which excavate dwellings for themselves in its 

 trunk and branches. (See " Forest Trees of Britain," 

 vol. ii. p. 65.) 



1. POLYGONUM (Persicaria). Perianth deeply 5-cleft, 

 not falling off ; stamens 5 8 ; styles 2 or 3 ; fruit a 

 triangular or flattened nut. (Name in Greek signifying 

 having many knees, or joints, from the numerous joints 

 of the stem.) 



2. RUMEX (Dock). Perianth deeply 6-cleft, in two 

 rows, the interior segments large ; stamens 6 ; styles 3 ; 

 fruit a triangular nut, covered by the enlarged inner 

 perianth. (Name, the Latin name of the plant.) 



3. OXYRIA (Mountain-Sorrel). Peria.nth deeply 4- 

 cleft, in two rows, the interior segments large ; stamens 

 6 ; styles 2 ; fruit a flattened nut with a membranous 

 wing. (Name from the Greek oxys, sharp, from the acid 

 flavour of the stem and leaves.) 



1. POLYGONUM (Persicaria). 

 * Styles 3 ; fruit triangular. 



1. P. Bistorta (Bistort, Snakeweed). Stem simple, 

 erect, bearing a single dense spike ; leaves egg-shaped, 

 the lower ones on winged stalks. Moist meadows, not 

 common. A rather handsome plant, with a large twisted 

 root, and several stems 1 1^ foot high, each of which 

 bears a cylindrical spike of flesh-coloured flowers. The 

 English names Bistort (twice twisted) and Snake-weed 

 were given in allusion to the form of the root. Fl. June. 

 Perennial. 



2. P. viviparum (Viviparous Bistort). Stem simple, 

 erect, bearing a single loose spike which has in the lower 

 part small bulbs in place of flowers ; leaves very narrow, 

 their margins rolled back. Mountain pastures, especially 

 in the Highlands of Scotland. A slender plant, 6 8 

 inches high, remarkable for its tendency to propagate 

 itself by small, red bulbs, which supply the place of 



