Novon 13: 386. 2003.
Biennials; short-lived; sexual; caudex not evident. Stems 1 per plant, arising from center of rosette near ground surface, (1.5–)3–11 dm, glabrous throughout. Basal leaves: blade obovate to oblanceolate, (4–)10–40 mm wide, margins serrate or dentate, ciliate-mucronate on teeth, trichomes often minute, surfaces glabrous or sparsely pubescent, trichomes simple, 0.1–0.6 mm. Cauline leaves: 7–15, often concealing stem proximally; blade auricles 3–12(–17) mm, surfaces of distalmost leaves glabrous. Racemes 16–45-flowered, sometimes branched. Fruiting pedicels suberect to divaricate-ascending, straight to slightly curved, 5–23 mm, glabrous. Flowers ascending at anthesis; sepals glabrous; petals white, 3–5 × 1–1.5 mm, glabrous; pollen ellipsoid. Fruits divaricate-ascending, not appressed to rachis, rarely somewhat secund, curved, edges parallel, (4–)6–11.7 cm × 1–2 mm; valves glabrous; ovules 50–80 per ovary; style 0.1–0.7(–1) mm. Seeds uniseriate, 1.2–2.2 × 0.8–1.4 mm; wing continuous, 0.1–0.3 mm wide distally. 2n = 14.
Phenology: Flowering Mar–May.
Habitat: Rocky bluffs, cedar glades, wooded hillsides, floodplains
Elevation: 100-500 m
Ont., Que., Ala., Ark., Conn., Del., D.C., Ga., Ill., Ind., Iowa, Ky., Md., Mass., Mich., Mo., N.H., N.J., N.Y., N.C., Ohio, Okla., Pa., S.C., Tenn., Vt., Va., W.Va., Wis.
The taxon sometimes treated as Arabis laevigata var. missouriensis is here recognized as a separate species (Boechera missouriensis) based on its significantly longer petals (5–10 versus 3–5 mm) and distinctive, lyrate-pinnatifid basal leaves that persist well beyond anthesis.