POLYGONIFLORJE. 359 



ters being present in the Urticacefe. On the other side it is 

 related to the Curvembryae. The flowers are small, often 

 trimerous, regular and slightly perigynons (in Chloranthacea, if they 

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

 Syncarps are present in some Piperacea?, 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 ; gynoeceum 

 2-3 carpels, ovary unilocular with 

 fine basal, straight (orthotropous) 

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

 2-3-angular nut ; the embryo, with 

 mealv endosperm, is straight or 

 curved (Fig. 355 /f), 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, uui- FIG. 361.-J Diagram of IMeum ; B ot 

 ... r, i Rumex; C of Polygonunt faqopyrum; T> 



parous scorpioul cymes; in Polygonunt .., ' mu 



J of P. lapabhifoliwn. The ovules are in- 



the two bracteoles unite into a mem- d i catec i inside the ovaries ; bracts and 

 branous tube ; in Rheum and Rumex there bracteoles are not shown, 

 is only one bracteole. 



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

 (Pn 3 + 3) and 9 stamens (A3 3 + 3). The 3-winged nut is nut 

 enclosed by the perianth. 



Rumex (Dock, Fig. 3545) 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 R. acetosella. 



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

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

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



