416 POLYGON ACEJE 



ORD. LXIV. PoLYGONACEiE. — THE PERSICARIA FAMILY 



A considerable Order of herbaceous plants, chiefly natives of 

 temperate climates, bearing scattered, simple leaves with sheathing 

 membranous stipules, petioles dilated at the base and margins 

 revolute in the bud. The flowers are generally perfect, small, 

 numerous and growing in spikes or panicles, so that many 

 members of the Order are handsome plants. The perianth is 

 deeply 3 — 6-parted, often in 2 rows and coloured, imbricate in 

 bud, persistent ; stamens 5 — 8, opposite the leaves of the perianth ; 

 ovary superior, ovoid, 3-sided, or compressed, i-chambered, 

 i-ovuled; styles 1 — 3; fruit a hard, flattened, or triangular, inde- 

 hiscent nut, usually enclosed in, but not adherent to, the perianth. 

 The properties residing in the leaves and roots are sometimes 

 very different, the former being in many cases acid, and some- 

 times of an agreeable flavour, the latter nauseous and purgative. 

 The powdered root of several species of Rheum affords the 

 valuable medicine Rhubarb, and the leaf-stalks of the same plants 

 are much used for making tarts, their sharp taste being attributable 

 to the presence of oxalic and malic acids. The Common Sorrel, 

 Rumex Acetosa, is sometimes used in the same way as Rhubarb- 

 stalks, or as a salad ; but the species mostly employed in cookery is 

 R. scutdtus, a native of southern Europe. Other species of this 

 genus are the Docks, known as troublesome weeds in most regions 

 of the globe. The Buckwheat, or Beech wheat {Fagopyrum escu- 

 lentum), so called from the resemblance in shape between its 

 fruits and those of the Beech, is probably a native of Central Asia. 

 In America and some European countries the flour derived from 

 its seeds is made into cakes or bread ; but in England it is chiefly 

 cultivated as a food for pheasants, which are very partial to it. 



1. Polygonum. — Perianth deeply 5 -cleft ; stamens 5 — 8 ; styles 

 2 — 3 j fruit a triangular or flattened nut, not winged ; embryo at 

 one side of the seed ; cotyledons flat. 



*2. Fagopyrum. — Perianth 5-cleft ; stamens 8; styles 3; fruit 

 triangular, not winged ; embryo in the centre or axis of the seed ; 

 cotyledons large, leaf-like, and plaited. 



3. Oxyria. — Perianth deeply 4-cleft ; the 2 inner segments 

 larger ; stamens 6 ; styles 2 ; fruit a flattened nut with a mem- 

 branous wing ; embryo central. 



4. Rumex. — Perianth deeply 6-cleft, the 3 inner segments much 

 larger ; stamens 6 ; styles 3 ; fruit a triangular nut, covered by the 

 enlarged inner perianth-segments ; embryo lateral. 



1. Polygonum (Persicaria). — Herbaceous plants with stems 

 often enlarged and bent at their nodes ; leaves scattered, with 



