CETTCrlFERJE. 81 



IV. -VITATERCRESS. NASTUETITJM. 



Glabrous perennials or annuals, with the leaves often pinnate, or pin- 

 nately lobed, and small white or yeUow flowers. Calyx rather loose. Stigma 

 capitate, nearly sessile. Pod linear or oblong, and usually curved, or in 

 some species short Uke a sihcule, the valves very convex, with the midrib 

 scarcely visible. Seeds more or less distinctly arranged in two rows in each 

 cell, and not winged. Radicle accumbent on the edge of the cotyledons. 



A small genus, but widely spread over the wliole area of the family. It 

 differs from Sisymbrium only in the position of the radicle in the embryo ; 

 and the wliite-flowered species are only to be distinguished from Bittercress 

 by the seeds forming two more distinct rows in each cell of the pod. 



Pod usually half an inch long or more. 



Flowers white 1. Common W. 



Flowers yellow 2. Creeping W, 



Pod usually ^ inch long or less. Flowers yellow. 



Pod oblong, curved. Petals scarcely longer than the calyx .... 3. Marsh W. 



Pod OToid, straight. Petals longer "than the calyx 4. Great W. 



1. Common ^Vatercress. ' Nastnrtiiun officinale, Sr. 



(Sist/iiibrium Nasturtium, Eng. Bot. t. 855.) 

 Stem much branched, sometimes very short and creeping, or floating in 

 shallow water ; sometimes scrambling on banks or bushes to the length of 

 2 feet or more. Leaves pinnate, with distinct segments, the terminal one 

 usually longer, ovate or orbicular. Flowers small and white, in short 

 racemes. Pods about 6 or 8 lines long or rather mor«, on spreading 

 pedicels, but slightly curved upwards, the double rows of the seeds very 

 distinct. 



Along brooks and rivulets, throughout Europe and Russian Asia, except 

 the extreme north, and naturalized in North America. Abundant in 

 Britain except in some of the Scotch Highlands. Fl. the whole summer. 



2. Creeping 'WTatercress. Nasturtium sylvestre, Br. 



{Sisymbrium, Eng. Bot. t. 2324.) 



Stem creeping at the base, the flowering branches erect or ascending, a 

 foot high or more. Leaves all or most of them deeply pinnatifid or almost 

 pinnate, the lower lobes distinct and narrow, the terminal one often larger 

 and broader. Flowers yellow and small, although the petals are consider- 

 ably longer than the calyx. Pod nearly that of the common W., but rather 

 more slender, and the two rows of seeds rather less distinct. 



On river-banks and in wet places, distributed over Europe and Russian 

 Asia, but apparently tiot so far north as the comm,on W. Sparingly scat- 

 tered over England and Ireland, and stiU more rare in Scotland. Fl. 

 summer. 



3. Marsli TVatercress. Nasturtium palustre, DC. 



{Sisymbrium terrestre, Eng. Bot. t. 1747. Nasturtium terrestre, Brit. Fl. 



Yellow Cress.) 

 Much resembles the creeping W., but usually weaker and not so tall, the 

 lobes of the leaves rather broader and more toothed, the petals seldom 

 .exceed the calyx, and the pod is seldom above 3 lines long, slightly curved, 

 the seeds much crowded, in two distinct rows in each cell. 



