Boechera cascadensis

Windham & Al-Shehbaz

Harvard Pap. Bot. 11: 260. 2007.

Basionym: Arabis microphylla var. thompsonii Rollins Rhodora 43: 429. 1941,
Treatment appears in FNA Volume 7. Treatment on page 369. Mentioned on page 364, 370, 390.

Perennials; long-lived; (cespitose); apomictic; caudex somewhat woody. Stems usually 1 per caudex branch, arising from center of rosette near ground surface, 0.5–2.2 dm, sparsely pubescent proximally, trichomes simple and short-stalked, 2- or 3-rayed, 0.1–0.2 mm, glabrous distally. Basal leaves: blade linear-oblanceolate, 0.7–2 mm wide, margins entire, ciliate proximally, trichomes to 0.4 mm, surfaces densely pubescent, trichomes short-stalked, (2- or) 3–6-rayed, 0.05–0.2(–0.3) mm. Cauline leaves: 4–6, not concealing stem; blade auricles 0.5–1 mm, surfaces of distalmost leaves glabrous. Racemes 3–11-flowered, unbranched. Fruiting pedicels ascending to divaricate-ascending, straight, 3–8 mm, glabrous. Flowers ascending at anthesis; sepals glabrous or sparsely pubescent; petals lavender, 5–6 × 1–1.7 mm, glabrous; pollen spheroid. Fruits ascending to divaricate-ascending, not appressed to rachis, not secund, straight, edges parallel, 3.5–6.2 cm × 1.2–1.5 mm; valves glabrous; ovules 58–80 per ovary; style 0.8–1.5 mm. Seeds uniseriate, 1.1–1.3 × 0.9–1 mm; wing continuous, 0.05–0.1 mm wide.

Phenology: Flowering Jun.
Habitat: Basaltic cliffs and rocky slopes in subalpine areas
Elevation: ca. 1900 m


Of conservation concern.

Morphological evidence suggests that Boechera cascadensis is an apomictic species that arose through hybridization between B. microphylla and B. paupercula (see M. D. Windham and I. A. Al-Shehbaz 2007 for detailed comparison). It is known from two collections: the type specimens from Kittitas County, Washington, and a more recent collection from Baker County, Oregon.

Selected References


Lower Taxa