POLYPETALOUS EXOGENOUS PLANTS. 297 



leaves ; sometimes scarcely 1° high, with leaves 2"-3" wide ; 

 then again in favorable situations attaining the height of 

 4°-6°, and the leaves l'-2' in breadth; calt/z-t\ibe with 

 acute scales. — Torrey and Gray. 



E. ViiiGixiANUM, Lam. Leaves linear-lanceolate and 

 linear-uncinately-serrate ; leaves of the involucre 7-8, 

 usually longer than the heads, 3-cleft or dentate-spiny; 

 scales tricuspidate; stem H°-5° high, cymosely branched, 

 and often compound at the summit, fistulous; radical and 

 lower cauline leaves usually 5"-10" Avide, but sometimes 

 very narrow, tapering at each end; the teeth remote and 

 indistinct ; heads numerous, f in diameter, pale blue or 

 nearly white ; calyx-iwh^ imbricated with acute lanceolate 

 vesicles. — Torrey and Gray. 



DAUCUS. Carrot. 



Calyx 5-toothed; corolla irregular; fruit oblong or 

 ovate ; carpels with 9 unequal bristly or prickly ribs, 

 and a single vitta under the larger ribs. — Annual or 

 biennial herbs, with pinnately finely-dissected leaves and 

 involucre, and yellowish or white blossoms. 



D. PUSILLUS, Michx. Stem rough with reflexed rigid 

 hairs; leaves twice pinnate, with the divisions linear; 

 bristles of the fruit barbed. Stem l°-3° high ; umbels long- 

 ped uncled. 



CICUTA. Water Hemlock. 



Calyx 5-toothed ; carpels with 5 flattish equal ribs, the 

 intervals with single vittae, and 2 on the inner surface. — 

 Smooth perennial marsh hej'bs, with hollow stems, and 

 twice pinnately or ternately divided leaves; involncels 

 many-leaved ; floiuers white ; fruit roundish. 



