132 CRUCIFER^E. 



Herbs growing in water or wet places, smooth or simply 

 hirsute ; with annual, biennial, or perennial roots, and branch- 

 ing stems which are frequently rooting below. Leaves usu- 

 ally lyrately toothed or pinnatifid, or pinnately parted ; the 

 petioles often auriculate-dilated at the base. Flowers small 

 or minute, yellow or white ; the racemes prolonged in fruit. 



Etymology. An old name for several pungent Cruciferous plants, said 

 to be compounded of nasus and tortus, from their effect upon the nostrils. 



Geographical Distribution, &c. A cosmopolite genus, the species of 

 which are of difficult extrication, especially those of the section Brachylo- 

 bos, DC, which have for the most part yellow or yellowish flowers. The 

 Water-Cress is the type of a peculiar section of the genus (Cardaminum, 

 DC). While many species bear linear siliques, others by gradual transi- 

 tion have oblong, elliptical, ovoid, or even globular silicles, some of which 

 C. A. Meyer therefore refers to Cochlearia § Armoracia. Indeed, the white- 

 flowered N. lacustre, Gray, ined.,* is so exactly an Armoracia as to con- 

 vince me that that group, if it can be detached from Cochlearia, will have to 

 be appended to the present genus ; — which, taken as a whole, would be 

 more naturally placed among Alyssineae than in Arabideae. — The Ameri- 

 can N. palustre (which usually has shorter pods than the European plant) 

 sometimes exhibits 3 - 4-carpellary and completely 3-4-celled ovaries. 



PLATE 53. Nasturtium sessiliflorum, Nutt. ; — a small specimen 

 (from St. Louis, Engelmann) ; natural size. (Excl. fig. 1 -5.) 



1. Diagram of the flower of N. palustre, the common North American 



plant so called. 



2. An enlarged flower of the same. 



3. Stamens and pistil ; and 4, inside view of a stamen, more enlarged. 



5. Pistil and receptacle, more magnified. 



6. Silique of N. sessiliflorum, enlarged ; one valve and most of the 



seeds detached. 



7. Tissue from the partition, highly magnified. 



8. A seed ; and 9, section across the accumbent cotyledons and radicle ; 



magnified. 



* The Nasturtium natans, Hook. FL. Bor.-Jlm., Torr. fy Gr. Fl., &c. (N. na- 

 tans 8. Americanum, Gray, in Jinn. Lye. N. Y.) Its flowers are much larger 

 than in N. natans, DC. (which is the Cochlearia amphibia, ft. Mryer) ; the 

 white petals are twice the length of the calyx, and there is no partition to the 

 pod, except a narrow border. 



