238 



MANUAL OP BOTANY 



where it is occasionally used as an ingredient in pickles. Its 

 ashes also yield barilla. Some authors regard this genus as 

 belonging to Chenopodiacese. 



Order 8. Polygonace^, the Buckwheat Order. — Cha- 

 r a c t e r. — Herbs or rarely shrubs. Leaves alternate, simple, com- 

 monly with ochreate stipules above the swollen joints (nodes) of 

 the stem, or rarely exstipulate. Flowers perfect, or sometimes 

 unisexual. Calyx inferior of from 3 — 6 sepals, more or less per- 

 sistent, imbricate. Stamens few, hypogynous or rarely peri- 

 gynous ; amthers dehiscing longitudinally. Ovary superior, 

 l-ceUed ; styles and stigmas 2 — 8 ; ovule solitary, orthotropous. 

 Fruit usually a triangular nut, and commonly enveloped in the 

 persistent calyx. Seed solitary, erect ; generally with farina- 

 ceous albumen. 



Diagnosis. — Usually herbs with ochreate stipules. Leaves 

 simple, alternate. Calyx inferior, persistent, imbricate. Stamens 

 definite. Ovary 1-ceUed; styles and stigmas 2 — 8. Fruit 



Fig. 997. 



Fig. 998. 



Fig. 997. Flower of 

 a species of Polygo- 

 num. Fig. 998. 



Pistil of a species 

 of Rumex. 



triangular. Seed solitary, erect, usually with mealy albumen, 

 radicle superior. 



Distribution and Numbers. — Generally diffused over the 

 globe, and more particularly so in temperate regions. Illus- 

 trative Genera : — Kheum, Linn. ; Polygonium, Linn. ; Cocco- 

 loba, Jacq. ; Eumex, Linn. There are about 500 species. 



Properties and Uses. — Chiefly remarkable for the presence 

 of acid, astringent, or purgative properties. The acidulous 

 character is principally due to the presence of salts of oxalic 

 acid. The fruits and roots of several species are more or less 

 nutritious. 



Series 2. — Multiovulatce aquaticce. 



Order 9. Podostemacb^, the Podostemon Order. — 

 Character. — Aquatic herbs with the aspect of Mosses or 

 Liverworts. Leaves minute and densely imbricate, or finely 



