CRUCIFER^E. (MUSTARD FAMILY.) 67 



rootstock, simple ; leaflets 7 - 13, those of the lower leaves rounded and stalked; 

 of the upper ones oblong- or linear, entire, or slightly angled-toothed ; petals 

 (white or rose-color) thrice the length of the calyx. — Wet places and bogs, 

 Vermont to New Jersey, Wisconsin, and northward : rare. May. (Eu.) 

 * * * Root mostly biennial or annual : leaves pinnate : flowers small, white. 



5. C. hirsuta, L. (Small Bitter Cress.) Beset with scattered hairs, 

 or glabrous ; stems (3' - 12' high) erect or ascending from the spreading cluster 

 of root-leaves ; their leaflets rounded, those of the upper leaves oblong or linear 

 and often confluent, all either toothed, angled, or entire; pods linear, slender, 

 erect or ascending in line with the pedicel ; style very short or almost none. 

 (C. Pennsylvania, Muhl. ; usually taller and more leafy-stemmed than the true 

 European C. hirsuta, the stamens always 6, and the pods less erect.) — Wet 

 places: common. May -July. (Eu.) 



Var. sylvatica (C. sylvatica, Link., C. Virginica, Michx.) grows in drier 

 places, is more slender, and has pods more erect than their ascending or spread- 

 ing pedicels, the style evident. — Commoner southward. (Eu.) 



5. ARAB IS, L. Rock Cress. 



Pod linear, flattened ; the valves plane or convex, more or less 1 -nerved in 

 the middle, or longitudinally veiny. Seeds usually margined or winged. Coty- 

 ledons accumbent. — Leaves seldom divided. Elowers white or purple. (Name 

 from the country, Arabia. See Linn. Phil. Bot. § 235.) 



§ 1. Seeds in one row in each cell, being nearly as broad as the partition. 

 # Low, chiefly biennials, diffuse or spreading from the base. 



1 . A. LudOViciana, Meyer. Nearly glabrous, often annual ; leaves all 

 jnnnately parted into oblong or linear few-toothed or entire divisions, those of 

 the lower leaves numerous ; flowers small, white ; pods rather broadly linear 

 and spreading, flat ; seeds wing-margined. (Cardamine Ludoviciana, Hook.) — 

 Open grounds, Virginia 1 to Illinois and southward. 



2. A. lyrata, L. Boot biennial ; plant mostly glabrous, except the lyrate- 

 pirtnatifld root-leaves, stem-leaves scattered, spatulate or linear with a tapering 

 base, sparingly toothed or entire ; petals white, much longer than the yellowish 

 calyx ; pods long and slender, flat, ascending or spreading ; the seeds margin- 

 less. — On rocks, New England to Kentucky along the mountains, Minnesota 

 and northward. April -July. — Radicle sometimes oblique, or even dorsal. 



A. ThaliAna, L., resembles the last, but the root-leaves are hardly if at all 

 lyrate, the stem more strict, flowers smaller, and the cotyledons uniformly in- 

 cumbent ; so it is referred to Sisymbrium, p. 70. 



3. A. petrsea, Lam. Root perennial, multicipital ; leaves sparingly pinna- 

 tifid-toothed or incised, sometimes entire ; petals rose-color or nearly white ; pods 

 shorter and less flat than in A. lyrata : otherwise similar. — Rocks, L. Superior ? 

 Willoughby Mountain, Vermont, H. Mann. 



4. A. dentata, Torr. & Gray. Roughish-pubescent, slender (l°-2° 

 high) ; leaves oblong, very obtuse, unequally and sharply toothed ; those of the 

 stem numerous, half-clasping and eared at the base, of the root broader and 

 tapering into a short petiole ; petals (whitish) scarcely exceeding the calyx, 



