Biennials; short-lived; sexual; caudex present or absent. Stems usually 2-4 per plant or caudex branch, arising from margin of rosette near ground surface, or arising laterally proximal to sterile shoots, 2-6 dm, pubescent proximally, trichomes short-stalked, 2-4-rayed, 0.15-0.4 mm, sparsely pubescent or glabrous distally. Basal leaves: blade obovate to oblanceolate, (6-)10-45 mm wide, margins dentate, not ciliate, surfaces sparsely pubescent, abaxially trichomes short-stalked, 3- or 4-rayed, 0.15-0.4 mm, adaxially simple ones, 0.4-1 mm. Cauline leaves: 4-20, rarely concealing stem; blade auricles 1-8 mm, surfaces of distalmost leaves sparsely pubescent. Racemes 14-66-flowered, sparingly branched. Fruiting pedicels divaricate-ascending to slightly descending, straight, 1-6 mm, glabrous or pubescent, trichomes appressed, branched. Flowers divaricate at anthesis; sepals glabrous or sparsely pubescent; petals white or cream, 2-3.5 × 0.7-1 mm, glabrous; pollen ellipsoid. Fruits divaricate-ascending to slightly descending, not appressed to rachis, not secund, straight or slightly curved, edges parallel, 1.3-4.2 cm × 0.7-0.8 mm; valves usually sparsely pubescent throughout, rarely glabrous; ovules 14-44 per ovary; style 0.1-0.5 mm. Seeds uniseriate, 0.7-1.1 × 0.5-0.6 mm; not winged. Flowering Apr-Jun. Bluffs and rocky ledges, wooded slopes, floodplains; 100-300 m; Ont.; Ala., Ark., D.C., Ill., Ind., Iowa, Kans., Ky., Md., Mich., Minn., Mo., Nebr., N.Y., Ohio, Okla., Pa., S.Dak., Tenn., Va., W.Va., Wis. Sisymbrium dentatum Torrey is an illegitimate name that pertains to Iodanthus dentatus.