Harvard Pap. Bot. 11: 78. 2006.
Perennials; usually short-lived; sexual; caudex not woody. Stems usually 1 per caudex branch, arising from center of rosette near ground surface, 2.5–9 dm, densely pubescent proximally, trichomes short-stalked, 2–6-rayed, 0.1–0.7 mm, similarly pubescent distally. Basal leaves: blade oblanceolate, 1.5–7 mm wide, margins entire or shallowly dentate, ciliate at petiole base, trichomes to 0.9 mm, surfaces densely pubescent, trichomes short-stalked, 5–10-rayed, 0.1–0.25 mm. Cauline leaves: 16–42, concealing stem proximally; blade auricles 0.5–1.5 mm, surfaces of distalmost leaves pubescent. Racemes 17–96-flowered, usually unbranched. Fruiting pedicels reflexed, abruptly recurved at base, otherwise straight, 7–13 mm, pubescent, trichomes appressed, branched. Flowers descending at anthesis; sepals pubescent; petals white, 6–9 × 1–2.5 mm, sparsely pubescent abaxially; pollen ellipsoid. Fruits strongly reflexed, usually appressed to rachis, sometimes somewhat secund, straight, edges parallel, 3.5–7.2 cm × 1.2–1.5 mm; valves densely pubescent; ovules 74–110 per ovary; styles 0.05–0.2 mm. Seeds uniseriate, 0.9–1.2 × 0.7–1 mm; wing continuous, 0.05–0.1 mm wide.
Phenology: Flowering late Apr-early Jun.
Habitat: Rocky, gravelly, and sandy slopes in open areas
Elevation: 900-2500 m
Idaho, Mont., Oreg., Wash.
Boechera polyantha is closely related to B. retrofracta, but is easily distinguished by densely pubescent fruits and scattered trichomes on abaxial petal surfaces.
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