CtoXV. Order It. 253 



CARDAMINE PENNSYLVANIA, JIuhl. American Water Cress. 

 Smooth, branching ; leaves pinnate, leafets round- 

 ish-oblong, obtuse, angular, toothed ; siliques erect. 



Found in brooks and ponds, growing under water, except its 

 upper leaves and flowers. Leaves alternate, smooth, pinnate ; 

 leafets oblong, rounded at the end, with a few large teeth on 

 each side, the terminal leafet much exceeding the rest in size. 

 The leafets in the upper leaves are entire. Flowers small, 

 white. Pods narrow, erect, an inch or more in length. 

 Brighton.-^May. 

 CARDAMINE VIRGINICA ? L. Virginian Cress. 



Smooth, erect ; leaves pinnate, leafets spatulate, ob- 

 tuse ; siliques erect. 



Found on dry hills, much smaller than the preceding. Leafets 

 oblanceolate, lower ones obovate, some of them with a tooth ou 

 one side ; ciliate under a magnifier. Flowers white. May. 



271. SISYMBRIUM. 



SlSYfllBRlUM AMPHIBIUM. L. JLmpllilioUS Ci'CSS. 



Siliques declined, oblong-ovate ; leaves oblong-lan- 

 ceolate or pinnatirid, serrate ; petals larger than the 



calyx. 



Stem erect, furrowed, hairy when out of water. Leaves hairy 

 clasping at base, lyrate or pinnatifid, toothed. Flowers in ter- 

 minal racemes, small, yellow. Fruit oblong-oval, swelling, com- 

 pressed, obtuse at both ends, tipt with the style, supported by 

 slender, spreading pedicels. Ponds and wet places, the lower 

 leaves sometimes capillary. July. Perennial. 



272. ERYSIMUM. 



ERYSIMUM OFFICINALE. L. Hedge Mustard. 



Pods pressed close to the main stalk ; leaves runci- 



nate. L. 



The whole plant is more or less hairy, and attains the height 

 of about two feet. Stem round ; branches given off at a large 

 angle, and curving. Leaves lyrate-runciuate. The fruitful 

 branches are long and slender, covered with close, sessile pod?. 



