CRUCIFERJE. (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. hirstlta, 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. Pennsylvanica, 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 I -nerved in 

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

 ledons accumbent. Leaves seldom divided. Flowers 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 

 pinnately 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 ? to Illinois and southward. 



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

 pinnatifid 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. Kadicle 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, //. 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, 



