CRUCIFER^E. 29 



4. D. maxima Nutt. : leaves many, alternate, on long petioles, ter- 

 nate ; leafets sub-oval, incisely and acutely toothed, lateral ones lobed ; 

 axils naked ; racemes lateral and terminal. 



HAB. Woods. N. Y. and Penn. June. ' l[.Stem 18 20 inches 

 high. Leaves 57 ; leafets broad. Flowers in racemes, purple. 



13. BARBAREA. Broicn. 



Pod 4-sided, 2-edged ; valves awnless at the apex, con- 

 cave-carinate. Calyx equal at base. 



Tetradynamia. Siliquosa. 



B. vulgaris Brown : lower leaves lyrate, the terminal lobes round- 

 ish ; upper ones sessile, obovate, toothed ; pod 4-sided, tapering into a 

 slender style. Erysimum barbarea Linn. 



HAB. Fields. N. S. and N. to the Arctic regions. June. If. 

 Stem 1218 inches high, smooth. Flowers small, yellow, 

 corymbed. According to Dr. Hooker the best character between 

 this species and B. prcecox is in the pod, which is here scarcely 

 more than an inch long and tapers into a long slender style. 



Bitter Winter-cress. 



14. ARABIS. Linn. 



Pod linear ; valves flat, 1 -nerved in the middle. Seeds in 

 one row in each cell, oval or orbicular, compressed. Cotyle- 

 dons flat, accumbent. Tetradynamia. Siliquosa. 



1. A. sagittata De Cand. ; leaves subdentate. rough, with the pubes- 

 cence often branched ; radical ones ovate or oblong, attenuated into a 

 petiole ; those of the stem lanceolate, sagittate-cordate ; pedicels of 

 the length of the calyx ; pods stiffly erect. 



c. ovata De Cand. : leaves rough ; radical ones ovate, toothed ; 

 cauline ones clasping. A. ovata Poir. Turritis ovata Pursh. 



d. ollongata De Cand. : leaves rough ; radical ones ovate-dblong-. 

 toothed; cauline ones sagittate-amplexicaul. Turritis oblon gata 

 Raf. 



HAB. Rocks. N. S. N. to Arctic America. $ .Stem 1218 

 inches high, simple. Flowers small, white. A very variable 

 plant.. ^ 



2. A. hirsuta De Cand. : leaves dentate, pubescent or scabrous ; ra- 

 dical ones obovate-oblong, tapering into a petiole ; cauline ones ovate- 

 lanceolate ; pedicels as long as the calyx ; pod erect. Turritis hursuta 

 Jacq. 



HAB. Conn. June. $. Stem 6 12 inches high, hairy. Flow- 

 ers small, white. A specimen of this plant, gathered in Con- 

 necticut by Dr. Robbins, agrees very well with the foreign one, 

 from which it seems to me our A. sagittata is quite distinct. 



Hairy Tower Mustard. 



3. A. thaliana Linn. : stem branched ; leaves subdentate, pilose ; 

 the radical ones petiolate, ovate-oblong ; cauline ones few, sessile j 



3* 



