150 



CRUCIFERAE. 



[Vol.. II. 



10. Arabis brachycarpa (T. &. G.) Britton. Purple Rock-cress. (Fig. 1780.) 



Turritis brachycarpa T. & G. Fl. N. A. i: 79. 1838. 

 Arabis confints S. Wats. Proc. Am. Acad. 22: 466. 



1887. 

 A. brachycarpa Britton, Mem. Torr. Club, 5: 174. 1894. 



Biennial, somewhat glaucous, generally pur- 

 plish, glabrous except at the base, simple or 

 sparingly branched, i-3 high. Basal leaves 

 stellate-pubescent, obovate or spatulute, 1'-$' 

 long, dentate, narrowed into a petiole; stem 

 leaves sessile, auricled at the base, lanceolate or 

 oblong-linear, about i' long, entire or with a 

 few teeth; pedicels erect or spreading, $"-$" 

 long in fruit; flowers white or pink, 4" broad; 

 petals twice the length of the calyx; pods nar- 

 rowly linear, nearly straight, i'-3' long, i" 

 wide, loosely erect or ascending; seeds in 2 rows 

 in each cavity, oblong, wing-margined. 



Quebec to Manitoba and the Northwest Territory, 

 south to Massachusetts, western New York, Illi- 

 nois and Minnesota. June-July. 



ii. Arabis glabra (L.) Bernh. Tower Mustard. 

 (Fig. 1781.) 



Turritis glabra L. Sp. PI. 666. 1753. 



Arabis glabra Bernh. Verz. Syst. Erf. 195. 1800. 



Arabis per/oliata Lam. Encycl. i: 219. 1783. 



Biennial, erect, glabrous and decidedly glaucous above, 

 pubescent at the base, nearly simple, 2-4 high. Basal 

 leaves petioled, 2 / -io / long, oblanceolate or oblong, dentate 

 or sometimes lyrate, hairy with simple pubescence, or with 

 hairs attached by the middle; stem-leaves sessile, with a 

 sagittate base, glabrous, entire or the lower sparingly den- 

 tate, 2 / -6 / long, lanceolate or oblong, acutish; pedicels 2"- 

 6" long, erect; flowers yellowish-white, 2" broad; petals 

 slightly exceeding the calyx; pods narrowly linear, 2 / ~3 / 

 long, W wide, strictly erect and appressed; seeds in 2 

 rows, marginless, or narrowly winged; style none. 



In field? and rocky places, Quebec to southern New York and 

 Pennsylvania, west to the Pacific Coast. Appears in some places 

 as if not indigenous. Also in Europe and Asia. May-Aug. 



12. Arabis Holboellii Hornem. 



Holboell's Rock-cress. (Fig. 1782.) 



.1. /f,>lhoellii Hornem. Fl. Dan. 11: pi. 1879. 1827. 

 Arabis retrofracta Graham, Kdinb. Phil. Journ. 



1829, 344. 1829. 



Erect, simple or branching above, io'-24 r 

 high, stellate-pubescent, hirsute or even nearly 

 glabrous. Lower leaves spatulate or oblance- 

 olate, tufted, petioled, j'-2' long, obtuse, en- 

 tire or sparingly toothed; stem-leaves sessile, 

 erect, clasping by a narrow auricled base; 

 pedicels slender, reflexed or the upper as- 

 cending, 3" -5" long in fruit; flowers purple 

 or whitish, 3 "-4" long, becoming pendent 

 petals twice the length of the calyx; pods lin- 

 ear, i / -2 / long, slightly more than y 2 ' f wide, 

 drooping; seeds margined, indistinctly in 2 

 rows in each cell; style very short or none. 



Lake Nepigon (according to Macoun) and 

 throughout arctic America, extending south in 

 the Rocky Mountains and the Sierra Nevada to 

 New Mexico and California. Summer. 



