POLYPETALOUS EXOGENOUS PLANTS. 301 



erect; leaves bipiuiiately divided; segments pinnatifid ; 

 the lobes linear-oblong, rather acute ; itmhels opposite the 

 leaves, usually sessile; tunbel 2-3 rays; involucel of 4-5 

 ovate leaflets ; fruit linear-oblong, attenuated upward ; 

 ribs very prominent, much broader than the intervals. 

 Prairies and along rivers. — Gray and Torrey. 



POLYT^NIA, DC. 



Margin of the calyx 5-toothed; petals oblong, with a 

 long inflexed emarginate point; fruit oval, lenticularly 

 compressed on the back, glabrous, with a broad and even 

 tumid corky margin; the dorsal dish impressed; rihs 

 obscure, nearly immersed in the corky pericarp; intervals 

 with 2 vittae, the thickened corky margin filled with resin- 

 iferous tubes ; carpophore free, 2-cleft ; seed plano-convex. 

 — A glabrous herh, with bipinnately-divided leaves, the 

 uppermost opposite and often 3-cleft; tmihels terminal 

 and opposite the leaves ; involucre none ; involucel of 

 several setaceous leaflets; flowers bright yellow. 



P. NuTTALLii. Plant 2°-3° high ; root fusiform ; stent 

 rather stout, usually scabrous leafy ; leaves on long pe- 

 tioles; the segments pinnately incised or toothed, those at 

 the base of the peduncles often only 3-cleft, with entire or 

 sparingly-toothed lobes ; rays of the umbel 12-20, about 

 an inch in length; fruit o' long, entire at each end. 

 Witchita Mountains. — Marcy, 



60. GINSENG FAMILY. Order, Araliaceje. 



Shrubs, trees, or perennial herbs, with compound or 

 simple exstipulate leaves ; flowers mostly umbellate, the 

 umbels often paniculate or racemed ; calyx adherent to 

 the ovary; the limb usually very small, entire or toothed; 

 petals 5-10, valvate in asstivation, very rarely none; sta- 

 mens as many as the petals and alternate with them; 



