596 



SYSTEMATIC BOTANY. 



formerly mucTi used as a purgative. The large roots of 7. macrorhiza 

 contain much farinaceous matter, and are eaten by the inhabitants of 

 Georgia and Carolina. 7. panditrata is the mechameck of the Indians of 

 North America ; its roots are said to be purgative and somewhat diuretic. 

 Tampico jalap, now much employed as a substitute for true jalap (see 

 Exogonium) in consequence of the scarceness of the latter, is derived from 

 Jpomoea simulans. 



Pharbitis ML— The seeds are known commonly in India under the name 

 of Kaladana seeds. They possess similar medicinal properties to our officinal 

 jalap, although not so powerful. 



Rhodorrhiza. — From the species of this genus, natives of the Canary 

 Islands, the volatile oil called Oil of Rhodium is said to be obtained. The 

 powdered wood is also used for snuff, and for fumigation. 



Natural Order 152. Cuscutace^is. — The Dodder Order {figs. 

 97i and 975). — Diagnosis. — This is a small order which is gene- 

 rally regarded as a sub-division of Convolvulacese. The plants 



Fig. 974. 



Fig. 975. 



Fig. 974. Corolla of Dodder (Cmcuta) laid open to show the scales and 

 stamens. Fig. 975. Spiral embryo of a species of Cuscuta. 



composing it are distinguished from that order by their para- 

 sitic habit {fig. 231); by the absence of leaves {fig. 231); by 

 the tube of their corolla being furnished with scales {fig. 974), 

 which alternate with its segments ; and by having a filiform 

 coiled embryo {fig. 975), with almost obsolete cotyledons. 



Distribution, cfr. — Chiefly natives of temperate climates. 

 There are about 50 species. 



Properties and Utes. — They are said to be purgative in their 

 action. They are often very destructive to Flax, Clover, and 

 other crops. 



Natural Order 153. Polemoniace^. — The Phlox Order. — 

 Character. — Herbs. Leaves opposite or alternate. Calyx 

 5-parted, persistent, generally regular. Corolla 5-lobed, with 

 contorted, or occasionally imbricated sestivation. Stamens 5, 

 alternate with the segments of the corolla ; pollen usually of a 

 blue colour. Ovary 3-celled ; style 1 ; stigma trifid. Fruit cap- 

 sular, 3-celled, 3-valved ; placenta axile. Seeds few or many ; 

 embryo straight in the axis of copious horny albumen ; cotyledons 

 elliptical, foliaceous. 



Distribution, ^r. — They abound most in the temperate parts 



