POLYPETALOUS EXOGENOUS PLANTS. 299 



DISCOPLEURA, DC. 



Cali/x-teeth subulate, persistent; ;;e/ff/s ovate, entire, 

 with a minute inflexed point; fruit ovate, somewhat 

 didymous ; carjjels with the 3 dorsal ribs filiform, prom- 

 inent, and rather acute, the 2 lateral ones united with a 

 thin corky accessory margin ; intervals with single vitt^e; 

 carpophore bihd ; seed somewhat terete ; leaves much dis- 

 sected, with setaceous segments ; leaflets of the involucre 

 pinnately 3-o-parted, or nearly entire ; floicers white. — An- 

 nual, glabrous herbs. — Torrey, 



D. NuTTALLii, DC. — Division of the leaves somewhat 

 verticillale ; involucre commonly less than half the length 

 of the rays; the leaflets sometimes 3-cleft, those of the 

 involucre mostly entire; umbels about 20-rayed; fritit 

 rather broader than long. Plant erect. — Gray and Torrey. 



D. CAPiLLACEA, DC. Umbels 3-10-rayed; leaves of 

 the involucre mostly 3-5-cleft ; fr uit o\ate. Stem l°-2° 

 high, much branched. Brackish marshes. 



THASPIUM, Nutt. 



Perennial herbs, with 1-2 ternately-divided leaves ; in- 

 volucre, none ; floiuers yellow or purple ; calyx-i^Qih. short 

 or obsolete; fruit ovoid or oblong, somewhat flattish 

 at the sides; carpels commonly equally and strongly 

 5-ribbed. 



Calyx-teeth obsolete. 



T. TRiFOLiATor, Gray. Stem l°-2° high ; leaves crenate, 

 the lowest usually simple and cordate, the others trifo- 

 liate ; leaflets ovate-lanceolate, obtuse at the base; fruit 

 roundish, ribbed or winged ; flojvers yellow or dark purple. 



