418 



MANUAL OF POISONOUS PLANTS 



Fig. 198. Kuropeaii Aristolochia (Aristolochia Clem- 

 ntitis). Flowering stem. Listed as a narcotic poison. 

 fAfter Faguet.) 



base; pistil 1 with superior ovary; fruit an achcne ; endosperm mealy, 

 tains a single family (Polygonaceae). 



Con- 



PoLYGONACEAE. Buckwlieat Family 



Herb.s, shrubs, or trees, often climbing; jointed stems; stipules in the form 

 of shcatbs ; juice often acrid or acid; leaves alternate or occasionally opposite; 

 flowers small, regular, mostly perfect; calyx more or less persistent; ovary 

 l-celled, bearing 2-3 styles or stigmas and a single erect ovule; fruit an 

 achenc, 3-4-angled or winged, invested by the calyx ; embryo curved or nearly 

 straight; endosperm mealy, copious. About 800 species. Of economic import- 

 ance are the pic plant (Rheum Rhaponticum) ; and rhubarb {R. officinale) of 

 Thibet, the root of which contains cathartic acid and is a powerful cathartic; 

 it also contains rhrysophan ^^t^^z^Pxa' ^""^diii C^^H^O^(OU)^, rhein 

 C,pHyO^(OIT)^ and chrysophanic acid C,,_lIj,0,.(0TI)2. It is purgative and 

 astringent. The canaigre (Rumex hymenoscpalus) produces a thick root valu- 

 able for tanning leather. It is a native of the southwest. The tannin is the same 



