68 TETRADYNAMIA. SILI^UOSA. 



binm. Mostly pubescent, calix and petals more or less- 

 yellow. Everywhere abundant on the banks of '.he Mis- 

 souri and Mississippi.. Ai.vulgare, f^ersoon {sylvestre. L. ) 

 Creeping Water Rucket. Sihque declinate, leaves (pseu- 

 do) pinnate; leaflets lanceolate, incisely serrate. Lin-. On 

 the g^raAelly banks of the Delaware, near Kensington, 

 Phiiadtlphia. Introduced? Agrees exactly with Sr J. E. 

 Smitii's, very accurate description. Flor. Bnt. 2. p. 701. 

 1 have never before seen ii in America. 5. * canescens. 

 Leaves pseudobipinnate, canescent; segments incisely 

 toothed, obi use; petals equal with the calix; silique cla- 

 vate, suberect, shorter than the peduncle. Hab. From 

 Vhg'inia to Geortria. S. Sophia? Ph. A much smaller 

 pU'trit than S. Sophia which it resembles only in habit, and 

 in fact approaches nearer apparently to S. album of Sibe- 

 ria. Leaves aboul 3 indies long, oblong, sessile, equally 

 covered wiih a whitish pubescence; pinnae about 7 pair, 

 nearly all equal in length, scarcely 1-2 an inch, ultimate 

 segments cuneate and arounded, about 3-toothed, den- 

 tui'es unequal. R .ceme terminal, petals very small, obo- 

 vate, pale yellow and about the length of the calix. Si- 

 lique linear-oblong, smooth, scarely more than half the 

 length of the peduncle, and terminated by a minute 

 style, 



A genus of more than 60 species principally indigenous 

 to Europe, there are also species in Nor'^iiern Africa and 

 in the Levant, a few are albo found in the southern hemis- 

 phere, at the Cape of Good Hope, in India, New Zealand, 

 and Terra del Fuego. 



461. ERYSIMUM. L. (Hedge mustard Winter 

 cress.) 

 Silique columnar, 4-sided. Calix closed. 



An heteromorphous and arbitrary genus, artificial, but 

 no way natural, inchiding- species scarcely distinct from 

 Sisymbrium, and Cheiranthus, the only genuine species is 

 considered to be E. officinale. 



Species. LE, officinale. Natural) zed, but not so very 

 common, as in England anM France. 2. parvijlonim. Per- 

 soon, (E. Cheirunthoides. L, an unmeaning and very ex- 

 ceptionable name which miglit be apphed to more tlian 

 half of the genus.) Hab. On the gravelly banks o\' the 

 Potomac, &c. Virginia, on the bar.ks of the Missouri, 

 arornd the Mandan viilagi s. 



The plants which have been referred to this genus are 

 almost exclusively European. 



