POLYPETALOUS EXOGENOUS PLANTS. 293 



Flowers white. Fruit ovoid. Calyx-limb 5-toothed. Divisions of the leaves 



fililonn DiscoPLEURA. 



Flowers white. Fruit oblong. Calyx-limb obsolete. Involucre 1-3-leaved, or 



none Helosciadium. 



Flowers white. Fruit globose. Calyx-teeth minute or none. Involucre 5-6-leaved. 



Leaves pinnate SiuM. 



Flowers yellow. Fruit ovoid-oblong. Leaves simple Bupi.eurum. 



Flowers yellow. Fruit ovoid-oblong, the intervals with 3 vittse Zizia. 



Flowers yellow or dark purple. Fruit ovoid or oblong, the intervals with single 



vittse Th ASPiuai. 



Flowers white. Fruit elliptical, with several vittse in each interval. .Liousticum. 



tt Fruit dorsally compressed, winged on the margins. 

 I Margins of thefi^it double-xvinged ; flowers white ; leaves pinnatdy compound. 



Carpels 3-ribbed on the back, the intervals with single vittae Angelica. 



Carpels 3-ribbed on the back, the intervals with 2 or more vittae. . . Archangelica. 

 Carpels S-winged on the back, the intervals with 2-3 vittse Conioselinum. 



Ill Margins of the fruit single-winged. 



Fruit broadly-winged. Marginal wings remote from the 3 dorsal ones. Leaves 



pimple, terete Tiedemannia. 



Fruit as in No. 19. Leaves pinnate or ternate Archemora. 



Fruit with all the ribs equidistant. Marginal flowers sterile. Plant woolly. 



Hera oleum. 

 § 2. Inner face of the seed concave. 



Fruit linear-oblong, narrowed toward the apex Chjsrophtixum. 



Fruit linear-clavate, narrowed toward the base Osmorrhiza. 



HYDROCOTYLE, Tourn. Marsh Pennywort. 



Calyx-teeth, obsolete ; petals not incurved ;/r?/iY laterally 

 compressed, orbicular; carpels 5-ribbed, the dorsal and 

 lateral ones often obsolete, the intermediate ones enlarged; 

 vittce none.— Low marsh herbs, with slender creeping sle7nSf 

 and peltate or reniform leaves; umbels small, axillary; 

 flowers white. 



H. Americana, L. Smooth ; leaves orbicular-reniform, 

 crenately 7-lobed; umbels sessile, 3-5-flowered ; fruit 

 2-ribbed; s^ews stoloniferous; ?caw5 very thin, glossy. 



