4. A. lævigàta, Poir. _Smooth_ and glaucous, upright; _stem-leaves partly clasping_ by the arrow-shaped base, lanceolate or linear, sparingly cut-toothed or entire; petals scarcely longer than the calyx; _pods long and narrow, recurved-spreading_ on ascending or merely spreading pedicels.--Rocky places, Maine to Minn. and southward. May. 5. A. Canadénsis, L. (SICKLE-POD.) Stem upright, smooth above; _stem-leaves pubescent, pointed at both ends_, oblong-lanceolate, sessile, the lower toothed; petals twice the length of the calyx, oblong-linear; _pods very flat, scythe-shaped, hanging_ on rough-hairy pedicels (2´´ wide).--Woods and ravines; not rare, especially westward. June--Aug. § 2. TURRÌTIS. _Seeds not so broad as the partition, in two more or less distinct rows in each cell, at least when young; strict and very leafy-stemmed biennials; cauline leaves partly clasping by a sagittate base. (Our species very glabrous, except the mostly hirsute base of the stem and the lower leaves.)_ 6. A. perfoliàta, Lam. (TOWER MUSTARD.) Tall (2--4° high), _glaucous_; stem-leaves oblong or ovate-lanceolate, entire; _petals yellowish-white, little longer than the calyx; pods very narrow_ (3´ long) _and pedicels strictly erect_; seeds marginless; cotyledons often oblique.--Rocks and fields, N. Eng. to Minn. (rare), north and westward. (Eu.) 7. A. confìnis, Watson. Scarcely glaucous, 1--3° high; pubescence below finely stellate; _stem-leaves lanceolate or oblong-linear_, entire (1--2´ long), with narrow auricles, or the lowest spatulate and toothed; _petals white or rose-color, fully twice the length of the calyx_; pedicels and flat _pods loosely erect, or ascending, or even spreading_; seeds wing-margined, when mature little narrower than the partition. (A. Drummondii, _Man._)--From the lower St. Lawrence to Minn., south to Conn., N. Y., and Ill.--Pods 2½--3½´ long, or in a var. (T. brachycarpa, _Torr. & Gray_) only 1--2´ long. § 3. PSEUDÁRABIS. _Seeds oblong or elliptical, very small, wingless, in one row; cotyledons often more or less oblique. Biennial or perennial, branching from the base._ 8. A. lyràta, L. 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.--On rocks or sandy shores, New Eng. to Ky. along the mountains, Minn., and northward. April--July.--Usually biennial, but southward in the mountains decidedly perennial. 9. A. dentàta, Torr. & Gray. Roughish pubescent, slender (1--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; _pods widely spreading, very slender, short-stalked; style scarcely any_.--N. Y. to Mich., Minn., and southward. May, June.