Boechera yorkii |
Boechera shockleyi |
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last chance rock cress |
Shockley's Rock cress |
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Habit | Perennials; long-lived; sexual; caudex woody. | Perennials; usually short-lived; sexual; caudex not woody, (rarely with persistent, crowded leaf bases). |
Stems | usually 1 per caudex branch, arising from center of rosette near ground surface, 1–3 dm, densely pubescent proximally, trichomes short-stalked, 4–7-rayed, 0.1–0.5 mm, mixed proximally with simple and short- to long-stalked, 2- or 3-rayed ones, to 1.5 mm, moderately pubescent distally. |
usually 1 per caudex branch, arising from center of rosette near ground surface, (0.8–)2–5 dm, densely pubescent proximally, trichomes short-stalked, 7–12-rayed, 0.1–0.2 mm, densely to sparsely pubescent distally. |
Basal leaves | blade linear-oblanceolate, 1.5–3 mm wide, margins entire, ciliate proximally, trichomes (simple and 2- or 3-rayed), to 1.5 mm, surfaces moderately pubescent, trichomes short-stalked, 4–7-rayed, 0.3–0.6 mm. |
blade oblanceolate, 3–10 mm wide, margins entire, not ciliate, surfaces densely pubescent, trichomes short-stalked, 7–12-rayed, 0.1–0.2 mm. |
Cauline leaves | 9–17, concealing stem proximally; blade auricles absent, surfaces of distalmost leaves moderately pubescent. |
14–60, concealing stem for most of length; blade auricles 0.5–4 mm, surfaces of distalmost leaves densely pubescent. |
Racemes | 8–35-flowered, usually unbranched. |
20–70-flowered, usually unbranched. |
Flowers | pendent at anthesis; sepals pubescent; petals yellowish proximally and brick-red distally or, rarely, one color throughout, 9–10 × 0.8–1 mm, glabrous; pollen ellipsoid. |
ascending at anthesis; sepals pubescent; petals lavender, 6–9 × 0.8–1.2 mm, glabrous; pollen ellipsoid. |
Fruiting pedicels | reflexed, straight, 1.5–2 mm, pubescent, trichomes appressed, branched. |
divaricate-ascending, straight, 7–28 mm, pubescent, trichomes appressed, branched. |
Fruits | (immature) reflexed, often appressed to rachis, not secund, straight, edges parallel, ca. 4 cm; valves pubescent throughout; style ca. 0.3 mm. |
divaricate-ascending, not appressed to rachis, not secund, usually curved, rarely straight, edges parallel, 4.5–11 cm × 1.5–2 mm; valves glabrous or sparsely pubescent throughout; ovules 140–190 per ovary; style 0.05–0.6 mm. |
Seeds | not seen. |
sub-biseriate, 1–1.3 × 0.7–0.8 mm; wing distal or, rarely, absent, 0.05–0.1 mm wide. |
Boechera yorkii |
Boechera shockleyi |
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Phenology | Flowering May. | Flowering Apr–May. |
Habitat | Crevices and ledges of calcareous rock outcrops | Rock outcrops (primarily dolomite) and gravelly soil in desert scrub, sagebrush, and pinyon-juniper woodlands |
Elevation | 2200-2400 m (7200-7900 ft) | 1200-2200 m (3900-7200 ft) |
Distribution |
CA |
CA; NV; UT
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Discussion | Boechera yorkii is immediately recognizable by its yellowish to brick-red petals and extremely short (1.5–2 mm), reflexed fruiting pedicels. It is known only from Last Chance Mountains in Inyo County. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Boechera shockleyi is a distinctive sexual species recognizable by the combination of strongly overlapping cauline leaves, a dense covering of minute, 7–12-rayed trichomes, and relatively long, curved, divaricate-ascending fruits with sub-biseriate seeds. It is most similar to B. inyoensis, but differs from that species in its narrower (0.8–1.2 versus 1.2–2 mm) petals, eciliate basal leaves with smaller (0.1–0.2 versus 0.2–0.7 mm) trichomes, greater number (140–190 versus 74–134) of ovules per ovary, and shorter (1–1.3 versus 1.7–2 mm) seeds with distal (versus continuous) wings. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 412. | FNA vol. 7, p. 406. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Arabis shockleyi | |
Name authority | S. Boyd: Madroño 51: 387, figs. 1–3. (2004) | (Munz) Dorn: Brittonia 55: 3. (2003) |
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