POLYGONIFLORJE. 



359 



fcers being present in the Urticacese. On the other side it is 

 related to the Curvembryge. The flowers are small, often 

 trimerous, regular and slightly perigynous (in Chloranthacece, if they 

 properly belong to this family, and Houttuynia, more or less epigynous). 

 Syncarps are present in some Piperaceae, but the fruit is generally 

 a single fruit, one-seeded berry, nut or drupe. The leaves are 

 generally scattered. 



Order 1. Polygonaceae. The majority are herbaceous plants 

 with round, often jointed stems, scattered leaves and ocrea, that is 

 a membranous, tubular, ligular or stipular structure inside the 

 base of the leaf, which clasps the stem and axillary bud ; the 

 edges of the lamina are rolled backwards in the bud. The flowers 

 are regular, small, generally , slightly perigynous, with incon- 

 spicuous, simple, green or white perianth of 5-6* free segments ; 

 stamens 5-9 (Fig. 354) sometimes 

 arranged in two series ; gynoaceum 

 2-3 carpels, ovary unilocular with 

 one basal, straight (orthotropous) 

 ovule, 2-3 free styles. The fruit is a 

 2-3-angular nut ; the embryo, with 

 mealy endosperm, is straight or 

 curved (Fig. 355 fl"), often unsym- 

 metrical. The inflorescences are com- 

 pound, and generally branch from the 

 axils of the bracteoles, so that the last 

 partial-inflorescences become coiled, uni- 

 parous scorpioid cymes ; in Polygonum 

 the two bracteoles unite into a mem- 

 branous tube ; in FJieum and Rumex there 

 is only one bracteole. 



FIG. 354. A Diagram of Rheum ; E of 

 Rumex; Cot Polygonnm J'agopyrum; D 

 of P. lapathifolium. The ovules are in- 

 dicated inside the ovaries ; bracts and 

 bracteoles are not shown. 



Eheum (Rhubarb, Fig. 354 A) has a 6-leaved, petaloid perianth 

 (Pn 3 + 3) and 9 stamens (A3 2 + 3). The 3-winged nut is not 

 enclosed by the perianth. 



Rumex (Dock, Fig. 354 B) has 6 stamens (A3 2 + 0); the perianth 

 is 6-leaved (Pr3 + 3), green or red, and the triangular nut is en- 

 veloped by the 3 interior perianth-leaves, which point upwards 

 and continue to grow after flowering. These perianth-leaves often 

 have warts on their outer surface. The following are monoecious : R. 

 acetosa and E. acetosella. 



Polygonum (Knot-grass, Figs. 354 C, D ; 355). The petaloid 

 perianth is most frequently 5-merous (-f spiral) ; 5-8 stamens. 

 The nut is triangular (Fig. 354 C, 355), or lenticular (Fig. 354 D). 



