Norl/i American Plants. 89 



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

 proximated so that their hroad 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. 



Hab. — Wet places on the priaries in the vicinity of Fort 

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

 Alabama ; Dr. M. C. Leavenworth.' 



Leavenworthia Michauxii. 



Style almost wanting ; radicle oblique. 



Cardamine uniflora, Michx .' fl. Bar. Anier. 2, p. 29 ; Pursh,fl. 2, p. 

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



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

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

 rare, Dr. Short-' 



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

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



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

 brium Sophia and S. sophioiiles, (lie dissepiment is marked with two very strong 

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

 areolae oblong and longitudinal. In S. oblueangulum and S. Columnie the tubuli 

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

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

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

 Cardamine Mcnzicsii, D. C and S. brachycarpitm, Richards.) the tubuli arc irre- 

 gular, but a large proportion of the areola? are linear and transverse, and the disso- 

 piment is 1-nerved. The funiculi are also adnate. Sisymbrium Thattanah&s no 

 midnervo to the dissepiment, and the tubuli are reticulated, forming oblong longi- 

 tudinal areola}. 



The tubuli in Arabis ambig-ua, I). 0. and A. pendula., I/inn. are descending, 

 forming tortuous parallel lines ; but in A. Turrita they are irregularly reticulated, 

 and thic 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 often of generic importance. 

 VOL. IV. 12 



