CRUCIFERAE. 



[VOL. II. 



4. Arabis dentata T. & G. Toothed 

 Rock-cress. (Fig. 1774.) 



Sisymbrium dentatum Torr. Transyl. Journ. 

 Med. 10: 338. Name only. 1837. 



Arabis dentata T. & G. Fl. N. A. i: 80. 1838. 



Slender, erect or ascending, i-2 high, 

 sparingly branching, finely rough-pubescent. 

 Basal leaves on margined petioles, obovate, 

 dentate, 2 / -4 / long, obtuse; stem-lea vessessile> 

 clasping by an auricled base, dentate, oblong 

 or oblanceolate; pedicels i // -2 // long, spread- 

 ing; flowers greenish-white, i // -2 // broad, the 

 petals hardly exceeding the calyx; pods nar- 

 rowly linear, io // -i5 // long, spreading; style 

 almostnone; seeds in i row in each cell, oblong, 

 marginless. 



Western New York to Minnesota, south to Ten- 

 nessee and Missouri. April-June. 



5. Arabis alpina L. Alpine Rock- 

 cress. (Fig. 1775.) 



Arabis alpina L. Sp. PI. 664. 1753. 



Erect or ascending, 4 / -i2 / high, densely 

 and finely pubescent. Basal leaves i / -2 / 

 long, obovate or spatulate, obtuse, dentate, 

 on margined petioles; stem-leaves ovate, ses- 

 sile, clasping by an auricled base, dentate; 

 flowers white, 2"-3" broad; petals much ex- 

 ceeding the calyx; pedicels slender, spread- 

 ing or ascending, 4" long in fruit; pods i'- 

 i #' long, curved upward, narrowly linear, \" 

 broad; seeds in I row in each cell, oblong, 

 narrowly winged; style scarcely any. 



Gaspe, Quebec, to Labrador, arctic America 

 and Alaska. Also in northern and central 

 Europe and in northern Asia. Summer. 



6. Arabis patens Sulliv. Spreading 

 Rock-cress. (Fig. 1776.) 



Arabis palens Sulliv. Am. Journ. Sci. 42: 49. 

 1842. 



Erect, i-2 high, mostly pubescent with 

 spreading hairs, at least below. Basal leaves 

 dentate, i'-3' long, on margined petioles; 

 stem-leaves i / -2 / long, ovate or oblong, acute 

 or acutish, sessile, dentate or nearly entire, 

 partly clasping by a cordate base; pedicels as- 

 cending, 6 // -8 // long in fruit, slender; flow- 

 ers white, 4" broad; pods i / -i>^ / long, %" 

 broad, narrowly ascending, not appressed; 

 seeds in i row in each cell, oblong, narrowly 

 winged; style i" long. 



Eastern Pennsylvania to Minnesota, south to 

 Alabama and Missouri. Summer. 



