Boechera cascadensis |
Boechera pulchra |
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Cascade rock-cress, Cascade suncress, Cascades rockcress, littleleaf rockcress |
beautiful rockcress |
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Habit | Perennials; long-lived; (cespitose); apomictic; caudex somewhat woody. | Perennials; long-lived; sexual; caudex 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. |
usually 1 per caudex branch, arising from center of leaf tufts, elevated above ground surface on woody base, (1.5–)3–7.5 dm, densely pubescent proximally, trichomes short-stalked, usually 4–7-rayed, 0.1–0.3 mm, similarly pubescent 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. |
blade linear to linear-oblanceolate, 1–3 mm wide, margins entire, not ciliate, surfaces densely pubescent, trichomes short-stalked, 4–9-rayed, 0.1–0.3 mm. |
Cauline leaves | 4–6, not concealing stem; blade auricles 0.5–1 mm, surfaces of distalmost leaves glabrous. |
10–30, often concealing stem proximally; blade auricles absent or, rarely, to 0.5 mm, surfaces of distalmost leaves pubescent. |
Racemes | 3–11-flowered, unbranched. |
8–25-flowered, usually unbranched. |
Flowers | ascending at anthesis; sepals glabrous or sparsely pubescent; petals lavender, 5–6 × 1–1.7 mm, glabrous; pollen spheroid. |
descending at anthesis; sepals pubescent; petals usually purple, rarely white, 9–16 × 2–4(–5) mm, sparsely pubescent or glabrous (trichomes scattered abaxially); pollen ellipsoid. |
Fruiting pedicels | ascending to divaricate-ascending, straight, 3–8 mm, glabrous. |
reflexed, abruptly recurved at base, otherwise straight, 8–16 mm, pubescent, trichomes appressed, branched. |
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. |
strongly reflexed, often appressed to rachis, sometimes somewhat secund, straight, edges parallel, 3.3–8 cm × 2.5–4 mm; valves pubescent throughout; ovules 68–106 per ovary; style 0.1–0.3 mm. |
Seeds | uniseriate, 1.1–1.3 × 0.9–1 mm; wing continuous, 0.05–0.1 mm wide. |
biseriate, 1.7–2.8 × 1.5–2.2 mm; wing continuous, 0.25–0.65 mm wide. |
Boechera cascadensis |
Boechera pulchra |
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Phenology | Flowering Jun. | Flowering Mar–Jun. |
Habitat | Basaltic cliffs and rocky slopes in subalpine areas | Rocky, gravelly or sandy slopes in chaparral, sagebrush and desert scrub communities |
Elevation | ca. 1900 m (ca. 6200 ft) | 800-2800 m (2600-9200 ft) |
Distribution |
OR; WA |
CA; NV; Mexico (Baja California)
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Discussion | 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. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Boechera pulchra is a distinctive diploid separated from related sexual species (B. formosa and B. lincolnensis) by abruptly recurved fruiting pedicels and purple flowers, and from apomictic hybrids (e.g., B. xylopoda) by having fruits densely pubescent throughout. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 369. | FNA vol. 7, p. 400. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Arabis microphylla var. thompsonii | Arabis pulchra |
Name authority | Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 260. (2007) | (M. E. Jones ex S. Watson) W. A. Weber: Phytologia 51: 370. (1982) |
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