68 TETRADYNAMIA. SILICtUOSA. 



bi\im. Mostly pubescent, calix and petals more or less^ 

 yellow. Kvei'} where abundant on the banks of the Mis- 

 souri and Mississippi. 4:.vuljar€, Persuon (si/hestre. L. ) 

 Creeping- ^V'ater Rocket. Silique declinate, leaves (pseii- 

 do) pinnate; leaflets lanceohUc, incisely serrate. Lin. On 

 the gravelly banks of tlie Delaware, near Kensin;.;ton, 

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

 Smith's, very accurate description. Fior. Brit. 2. p. 701. 

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

 Leaves pseudobipinnate, canescent; segments incisely 

 toothed, obluse; petals equal with the calix; siliqne cla- 

 vivte, suberect, shorter than the peduncle. Mab. Fronn 

 \~n-g-inia to fJeort^na. ;S'. Sophia? Ph. A much smaller 

 plant than S. Sophia which it resembles only in habit, and 

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

 ria. Leaves about 3 inches long-, oblong, sessile, equally 

 covered with a whitish pubescence; pinnae about 7 pair, 

 nearly all equal in length, scaictly 1-2 an inch, ultimaie 

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

 tures unequal. Raceme terminal, petals very small, obo- 

 vate, pale yellow and about the length (,f 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 indip;enons 

 to Europe, there are also species in Northern Africa and 

 in the Levant, a few arcjj^o 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 clo.sed. 



An heteromorphous and arbitrary genus, artificial, but 

 no v.ay natural, including species scarcely distinct from 

 Sisymbrium, and Cheiranthns, tlie only genuine species is 

 considered to be E. officinale. 



Species. L E. officinale. Naturalized, but not so very 

 com'non, as in England and France. 2. parviforum. Per- 

 soon, (T-v. Cheirunthoides.lj.' aw unmeaning and very ex- 

 ceptionable name which might be applied to more than 

 half of the genus.) Hab. On the gravelly banks of the 

 Potomac, &.C Virginia, on the banks of the Missouri, 

 around tl\e Mandan villages. 



The plants which have been referred to this genus are 

 almost exclusively European. 



