570 POLYGONUM. [CLASS VIII. ORDER II. 



pagation of its species against the contingencies of the circumstances 

 of its place of growth. 



** PERSICARIA. Tournef. Stem branched, each branch terminated 

 with a spike of flowers. Style divided to the middle or base. 

 Stigmas large, capitate. 



1. P. amphi'bium, Linn. (Fig. 646.) Amphibious Persicaria. Spike 

 oblong-ovate, dense, cylindrical ; flowers pentandrous ; styles two, 

 united half way up ; leaves petiolated, oblong, lanceolate, rough on 

 the margins; root creeping. 



English Botany, t. 436. English Flora, vol. ii. p. 232. Hooker, 

 British Flora, vol. i. p. 186. Lindley, Synopsis, p. 211. 



K. aquaticum. Leaves floating, broadly oblong lanceolate, quite 

 smooth, on long petioles. 



P. amphibium. ,. natans, Mrench. 



/9. terrestre, (Fig. 647.) Stem erect ; leaves lanceolate, on short 

 petioles; the whole plant rough, with short close pressed rigid hairs. 



Root in whorls of branched fibres, at various intervals on long 

 cylindrical creeping underground stems, putting out leaves and stems 

 from the joints, elongated and flexuous. Stem round, striated, scarcely 

 branched .in water, more frequently so when grown upon the land, 

 smooth or rough, with bristly points. Leaves alternate, arising from 

 a sheathing base, terminated in a thin membranous stipule, fringed or 

 torn, elevated on a footstalk of various lengths, sometimes in /3. terrestre 

 it is very short, and not unfrequently in a. aquaticum it is three or 

 four inches long, bearing elliptic oblong lanceolate leaves, more or less 

 heart-shaped at the base, quite smooth, as is the whole plant, green and 

 scarcely paler on the under side, with a stout mid-rib and very nume- 

 rous slender lateral netted veins; but in . terrestre the leaves are 

 lanceolate, narrow, often with a tapering point, dark green above, pale 

 beneath, and rough all over, as is the rest of the plant, with short close 

 pressed bristly points. Inflorescence a terminal spike of numerous 

 crowded flowers, on short footstalks, into an ovate or ovate oblong 

 cylindrical shape, of a pale pink or rose colour. Bractea of ovate 

 pointed membranous scales. Perianth deeply cleft into five oblong 

 obtuse segments. Stamens five, on slender filaments, mostly as long 

 as the perianth, the anthers small, roundish, of a dark colour. Styles 

 longer than the stamens, slender, united about half way up, and 

 bearing rather large fleshy capitate or globose stigmas. Fruit an ovate 

 compressed nut. 



Habitat. Lakes, rivers, ponds, and margins of ditches; frequent. 

 /5. banks and meadows. 



Perennial ; flowering from July to August. 



This is an extremely variable plant, from the circumstance of its 

 being capable of growing. both in water and on land, and from the 

 change which takes place in its appearance under these two different 



