Boechera peirsonii

Perennials; long-lived; (cespitose); apomictic; caudex woody. Stems usually 1 per caudex branch, arising from center of rosette near ground surface, 1–2.5 dm, glabrous or sparsely pubescent proximally, trichomes short-stalked, 2–5-rayed (rarely, some simple), 0.4–0.6 mm, glabrous distally. Basal leaves: blade oblanceolate, 2.5–6 mm wide, margins entire, ciliate proximally, trichomes (simple), surfaces densely pubescent, trichomes short-stalked, 4–7-rayed, 0.3–0.5 mm. Cauline leaves: 3–12, often concealing stem proximally; blade auricles 0.5–2 mm, surfaces of distalmost leaves usually glabrous, sometimes margins ciliate. Racemes 12–25-flowered, usually unbranched. Fruiting pedicels ascending to divaricate-descending, straight, 2–6 mm, glabrous. Flowers ascending at anthesis; sepals pubescent; petals purple, 5–6 × 1.5–2 mm, glabrous; pollen spheroid. Fruits ascending to divaricate-ascending, not appressed to rachis, not secund, straight, edges parallel, 2–3.7 cm × 2–2.8 mm; valves glabrous; ovules 56–80 per ovary; style 0.1–0.3 mm. Seeds uniseriate, 1–1.5 × 0.8–1 mm; wing distal or continuous, 0.05–0.1 mm wide.

Phenology: Flowering Jun–Sep.
Habitat: Granitic ledges and talus slopes
Elevation: 2700-3400 m

Calif.

Discussion

Boechera peirsonii is an apomictic species of unknown origin; although previously treated as a variety of Arabis (B.) breweri, it is quite distinct from that taxon (see M. D. Windham and I. A. Al-Shehbaz 2007 for detailed comparison). All known collections come from the San Bernardino Mountains of southern California, ca. 200 km distant from the nearest populations of B. breweri.

Selected References

None.

Lower Taxa