LXIL CHENOPODIACEJ2. 370 



On the seacoasts and In the saline districts of Europe, Asia, and 

 Africa, but not extending to[the Arctic regions. Not uncommon round 

 the British Isles. PI. summer and autumn. 



LXIII. POLYGONACE^. THE POLYGONUM FAMILY. 

 Herbs, or in some exotic species, shrubs, with alternate 

 leaves, and thin, scarious stipules, forming a sheath or ring 

 round the stem within the leafstalk. Flowers small, herba- 

 ceous or sometimes coloured, clustered in the axils of the leaves 

 or in spikes or racemes, forming terminal panicles. Perianth 

 of 6, 5, or fewer segments, regular and equal, or the inner ones 

 enlarged. Stamens variable in number, never more than 8 in 

 the British species. Ovary free, with a single ovule, but with 

 2, 3, or more styles or stigmas. Fruit a small, seed-like nut, en- 

 closed in the persistent perianth. Embryo of the seed straight 

 or curved, in a mealy albumen. 



A considerable Order, dispersed over every part of the globe, from 

 the hottest tropical plains to the extreme Arctic regions, or to the 

 highest mountain summits, close to the limits of perpetual snows. 

 Some tropical species are tall, woody climbers, or erect shrubs, but the 

 majority of the Order are herbs approaching Chenopodiacece in char- 

 acter, and sometimes in habit, but always readily known by their 

 sheathing stipules, even when reduced to a narrow ring or a mere line 

 surrounding the stem. They also very seldom acquire any of the 

 mealiness of Chenopodiacece. 



Fruiting perianth of 6 segments, 3 inner ones often enlarged . . 1. RUMEX. 

 Fruiting perianth of 4 segments, 2 inner ones enlarged . . .2. OXYIUA. 

 Fruiting perianth of 5 nearly equal segments 8. POLYGONUM. 



The Rhubarbs of our gardeners and druggists are species of the genus 

 Rheum, belonging to Polygonacece. 



1. RUMEX. DOCK 



Herbs or shrubs, the British species all perennials, with a thick root- 

 stock, and erect, furrowed annual stems ; the thin sheathing stipules 

 never fringed on the edge, but soon becoming torn or jagged. Lower 

 leaves stalked and often large. Flowers numerous, small, herbaceous, 

 though often turning red, usually pedicellate, in whorl-like clusters, 

 axillary or in terminal racemes, often branching into panicles. Perianth 

 deeply 6 -cleft ; when in fruit the 3 inner segments become enlarged 

 and close over the triangular nut. Stamens 6. Styles 3, very short 

 with often tubercled, fringed stigmas. 



A considerable genus, spread over the greater part of the world, 

 very readily distinguished from the rest of the Order, but the species 

 vary so much in appearance that it is often very difficult to fix their 

 real limits. They can also seldom be determined without the fruit- 

 ing perianth, from which most of the characters are taken. They 



