DICOTYLEDONOUS PLANTS. 



HAB. In water. Throughout the U. S. and to the N. W. coast. 

 June, July. 11. Stem decumbent, floating. Leaves large. 

 t'ltnnrs white, corymbed. Pod scarcely an inch long. Es- 

 teemed as a salad. Water-cress. 



%. N. palustrc De Cand. : leaves lyrate-pinnatifid ; lobes confluent, 

 unequally toothed, smooth; petals as long as the calyx ; pod obtuse at 

 both ends, turgid ; root fusiform. Suymtrimm.pAiftn IV'illd. I'lirs/i. 

 II \. Wet places. Through out .the U. S. and to the shores of 

 the Arctic sea. July. <>. Stem 18 inches high, mostly erect. 

 Lmrr.t jrlabrous, all more or less pinnatifid. FUncers numerous, 

 minute, yellow. Pod short. 



, 3. N. amphilium Brmrn : leaves oblong-lanceolate, lyrate-pinnati- 

 fid or serrate; root fibrous ; petals longer than the calyx; pod elliptical, 

 tipped with the mucronate style. Sisymbrium amphibnim Linn. 



HAB. Wet places. Throughout the U. S. and Can. June, July. 

 1. Stem 1 2'feet high. Flowers yellow, minute, in a long ra- 

 ceme. Very variable in the character of its leaves. 



4. N. natans De Cand. : emerged leaves lanceolate, entire, serrate ? 

 immersed ones doubly tripinnatifid ; segments capillaceous ; pouch 

 obovate-globose, with a style equal in length. 



HAB. In water. Near Montreal. Hook. Oneida Lake. Dr. 

 Asa Gray. July. 2J.. Stems long, submerged. Lower learcs 

 finely divided ; middle ones often pinnatifid ; emerged ones lan- 

 ceolate, undivided, serrate. Flmrcrs very pale yellow, smaller 

 than in the preceding. 



17. HESPERIS. Linn. 



Pod roundish, or about 4 cornered. 'Stigmas 2, erect, con- 

 riivcnt. Calyx bisaccate at base. Seeds somewhat 3-sided. 

 Stamens without teeth. Tetr adynamia. Siliquosa. 



1. H. matronalis Linn.: pedicels of the length of the calyx ; petals 

 obovate ; pod erect, torose, glabrous, not thickened on the margin ; 

 leaves ovate-lanceolate, toothed ; stem erect, nearly simple. 



HAB. Shores of Lake'Huron. Hook. Dame's Jlolet. 



2. H. ? pinnatifida Mich. : lower leaves lyrate-pinnatifid ; upper 

 ones lanceolate, unequally serrate ; border of the petals obovate, entire; 

 pedicels at length longer than the calyx. 



HAB. Woods. N. -S. Torr. W. to Ken. July. U.Stem a foot 

 high, very smooth. Flowers pale purple, small. 



18. SISYMBRIUM. All. 



Pod roundish, sessile upon the torus. Stigmas 2, some- 

 what distinct, or connate in a head. Calyx equal at base. 

 Seeds ovate or oblong. Cotyledons flat, incumbent, gome- 

 times oblique. Stamens without teeth. 



Tetradynamia. Siliquosa. 



