Biennials; short-lived; sexual; caudex not evident. Stems usually 1 per plant, arising from center of rosette near ground surface, 4-10 dm, glabrous throughout. Basal leaves: blade obovate to oblanceolate, 5-20 mm wide, margins dentate, not ciliate, surfaces glabrous or subapically puberulent, trichomes simple, 0.1-0.2 mm. Cauline leaves: 30-80, not concealing stem; blade auricles absent, surfaces of distalmost leaves glabrous. Racemes 70-150-flowered, multi-branched. Fruiting pedicels divaricate-ascending to horizontal, straight or gently recurved, 6-15 mm, glabrous. Flowers divaricate-ascending at anthesis; sepals glabrous; petals white, 2.8-4 × 0.6-1 mm, glabrous; pollen ellipsoid. Fruits divaricate-ascending to widely pendent, not appressed to rachis, not secund, straight or slightly curved, edges parallel, 4.3-7.9 cm × 1.5-1.8 mm; valves glabrous; ovules 30-42 per ovary; style 0.1-0.2 mm. Seeds uniseriate, 1.2-1.7 × 0.7-1 mm; wing continuous or, sometimes, distal (rarely absent), 0.1-0.2 mm wide. 2n = 14. Flowering Jul-Sep. Shale barrens and wooded slopes of crumbling shale; of conservation concern; 100-500 m; Va., W.Va. Boechera serotina is unique among members of the genus in its highly branched inflorescences and late (summer-fall) anthesis. It is in the Center for Plant Conservation´s National Collection of Endangered Plants.
Freely branched, the infl a panicle with numerous ±pendulous fls; lvs without auricles, but often soon deciduous; cal short, mostly 2-3 mm; frs 4-8 cm, straight or nearly so; 2n=14; otherwise much like no. 6. Shale-barrens of Va. and W.Va. July-Aug, well after no. 6 [Arabis laevigata (Muhl.) Poir.].
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.