I So 



CRUCIFERAE. 



Vol. II. 



4. Arabis dentata T. & G. Toothed 

 Rock-cress. Fig. 2072. 



Sisymbrium dentatum Torr. Transyl. Journ. Med, 

 10: 338. Hyponym. 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'-^' long, obtuse ; stem-leaves sessile, 

 clasping by an auricled base, dentate, oblong 

 or oblanceolate, obtuse or the upper acute; 

 pedicels l"-2" long, spreading; flowers green- 

 ish-white, l"-2" broad, the petals hardly ex- 

 ceeding the calyx; pods narrowly linear, 10"- 

 15" long, spreading; style almost none; seeds 

 in I row in each cell, oblong, marginless. 



Western New York to Minnesota, south to Ten- 

 nessee, Missouri and Kansas. April-June. 



5. Arabis alpina L. Alpine Rock-cress. 



Snow-drift. Fig. 2073. 



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



Erect or ascending, 4'-i2' high, densely and 

 finely pubescent. Basal leaves 1-2' long, obo- 

 vate or spatulate, obtuse, dentate, on margined 

 petioles; stem-leaves ovate, sessile, clasping by 

 an auricled base, dentate ; flowers white, 2"-3" 

 broad; petals much exceeding the calyx; pedi- 

 cels slender, spreading or ascending, 4" long in 

 fruit; pods I'-iY long, curved upward, nar- 

 rowly linear, i" 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. White allison. Bishop's-wig. 

 Dusty-husband. Summer. 



6. Arabis patens Sulliv. Spreading 

 Rock-cress. Fig. 2074. 



Arabis patens 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 marginal petioles ; stem- 

 leaves l'-2' long, ovate or oblong, acute or 

 acutish, sessile, dentate or nearly entire, partly 

 clasping by a cordate base; pedicels ascending, 

 6"-8" long in fruit, slender; flowers white, 4" 

 broad; pods I'-il' long, i'' broad, narrowly 

 ascending, not appressed ; seeds in I row in 

 each cell, oblong, narrowly winged; style l" 

 long. 



Eastern Pennsylvania to Minnesota, south to 

 Alabama and Missouri. Summer. 



