Boechera acutina

Biennials or perennials; short-lived; apomictic; caudex present or absent. Stems usually 1 per caudex branch, arising from center of rosette near ground surface, 1.5–6 dm, densely pubescent proximally, trichomes sessile, 2–4-rayed, 0.15–0.4 mm, usually sparsely pubescent distally, rarely glabrous. Basal leaves: blade oblanceolate, 1.5–6 mm wide, margins usually entire, rarely denticulate, ciliate proximally, trichomes (simple), to 0.5 mm, surfaces sparsely to moderately pubescent, trichomes sessile, 3–5 (or 6)-rayed, 0.15–0.35 mm. Cauline leaves: 2–20(–38), often concealing stem proximally; blade auricles 0.3–2 mm, surfaces of distalmost leaves sparsely pubescent or glabrous. Racemes 5–20(–36)-flowered, usually unbranched. Fruiting pedicels erect to ascending, usually straight, 3–10 mm, pubescent or glabrous, trichomes appressed, branched. Flowers ascending at anthesis; sepals pubescent; petals white or lavender, 5–7 × 0.9–1.3 mm, glabrous; pollen spheroid. Fruits ascending, not appressed to rachis, not secund, straight, edges parallel, 2.5–7.5 cm × 1.2–1.8 mm; valves glabrous; ovules 46–100 per ovary; style 0.3–1 mm. Seeds uniseriate, 1.8–2.2 × 1–1.4 mm; wing continuous, 0.1–0.4 mm wide.

Phenology: Flowering Jun–Jul.
Habitat: Gravelly slopes in meadows, open forests
Elevation: 1400-1900 m

Calif., Idaho, Oreg.

Discussion

Boechera acutina is an apomictic hybrid that clearly contains a genome derived from B. stricta; the other parent remains uncertain. Plants of B. acutina are superficially similar to B. pratincola and are often misidentified as Arabis (Boechera) divaricarpa; the species is easily distinguished from both of those (see M. D. Windham and I. A. Al-Shehbaz 2007b for detailed comparison).

Selected References

None.

Lower Taxa