North American Plants. 89 



usually 5, much compressed, suspended on short rigid funiculi, ap- 

 proximated so that their broad membranaceous margins somewhat over- 

 lap. Embryo nearly straight from the earliest to the most mature state. 

 The radicle points upward, at first inclined a little from the hilum, but 

 gradually approximating towards it. Cotyledons plano-convex. 



IIab. — Wet places on the prairies in the vicinity of Fort 

 Towson, Arkansas ; also in Texas, and in Jefferson County, 

 Alabama ; Dr. 21. C. Leavenworth ! 



Leavenworth i a Michauxii. 

 Style almost wanting; radicle oblique. 



Cardamine uniflora, Michx. I fl. Bor. Amer. 2, p. 29 ; Pursh, fl. 2, p. 

 439, D. C. ! syst. 2, p. 251. 



Hab. — On rocks about Knoxville, Tennessee, Michaw! 

 v. s. in herb. Mus. Paris. On wet rocks, Kentucky ; very 

 rare, Dr. Short! 



Obs. — This species is extremely like L. aurea, but ap- 

 pears to be distinct. In habit, and in the form and size of 



rican specie--, without, however, finding this character at all uniform. In Sisym- 

 briurn Sophia and S. sophioides, the dissepiment is marked with two very strong 

 nerves, extending from the base to the apex, and the tubuli are reticulated ; the 

 areola? oblong and longitudinal. In S. obtiisanfjubnii- and S. Columna the tubuli 

 form distinct waved descending lines. In S. officinale the dissepiment is opake 

 and nerveless; the tubuli very minute, indistinct and descending. In S. ca- 

 nescens, Nutt. (which seems to be identical with Erysimum pinnatwm, Walt. 

 Cardamine Menziesii, D. 0. and S. brachycarpum, Richards.) the tubuli are irre- 

 gular, but a large proportion of the areolae are linear and trausver.se, and the dis- 

 sepiment is 1 -nerved. The funiculi are also adnate. Sisymbrium ThaKana 

 has no midnerve to the dissepiment, and the tubuli are reticulated, funning 

 oblong longitudinal areolae. 



The tubuli in Arabia ornbigua, D. C. and A. pendula, Linn, are descending, 

 forming tortuous parallel lines ; but in A. Tvirrita they aro irregularly reti- 

 culated, and the areola amorphous. In A. Canadensis they are exceedingly 

 contorted and irregularly reticulated. Notwithstanding this variety in the 

 structure of the dissepiment, it is very constant in the same species, and the 

 characters derived from it are doubtless otten of generic importance. 



VOL. IV. i'A 



