2. A. pàtens, Sulliv. Downy with spreading hairs, erect (1–2° high); stem-leaves oblong-ovate, acutish, coarsely toothed or the uppermost entire, partly clasping by the heart-shaped base; petals (bright white, 4´´ long) twice the length of the calyx; pedicels slender, spreading; pods spreading or ascending, tipped with a distinct style.—Penn. to central Ohio and southward; Minn. April, May.
3. A. hirsùta, Scop. Rough-hairy, sometimes smoothish, strictly erect (1–2° high); stem-leaves oblong or lanceolate, entire or toothed, partly clasping by a somewhat arrow-shaped or heart-shaped base; petals (greenish-white) small, but longer than the calyx; pedicels and pods strictly upright; style scarcely any; immature seeds somewhat 2-rowed.—Rocks, common, especially northward. May, June. (Eu.)
[*][*][*] Erect and simple leafy-stemmed biennials (1–3° high), with small whitish flowers, recurved-spreading or pendulous flat pods (3–4´ long), and broadly winged seeds, their stalks adherent to the partition; root-leaves rarely lyrate.
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.