Boechera acutina

(Greene) Windham & Al-Shehbaz

Harvard Pap. Bot. 12: 236. 2007

Basionyms: Arabis acutina Greene Leafl. Bot. Observ. Crit. 2: 82. 1910
Synonyms: Arabis divaricarpa var. interposita (Greene) Rollins Arabis drummondii var. interposita (Greene) Rollins Arabis interposita Greene
Treatment appears in FNA Volume 7. Treatment on page 365. Mentioned on page 362, 374.
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

Distribution

V7 492-distribution-map.gif

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).

References

None.

Lower Taxa

No lower taxa listed.