Boechera arcuata |
Boechera bodiensis |
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arching rockcress, elegant rockcress |
Bodie Hills rock cress |
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Habit | Perennials; usually long-lived; sexual; caudex often woody (well-developed). | Perennials; long-lived; (cespitose); apomictic; caudex somewhat woody. |
Stems | usually 1 per caudex branch, arising from center of rosette, elevated on woody base or from ground surface, (2–)3–8 dm, densely pubescent proximally, trichomes short-stalked, 2-rayed and simple, to 1 mm, pubescent distally. |
usually 1 per caudex branch, arising from center of rosette near ground surface, 1.5–3.5 dm, densely pubescent proximally, trichomes short-stalked, 5–10-rayed, to 0.7 mm, sparsely pubescent or glabrous distally. |
Basal leaves | blade linear to oblanceolate, 2–7(–12) mm wide, margins usually entire, rarely denticulate, ciliate along petiole, trichomes to 1.5 mm, surfaces densely pubescent, trichomes usually short-stalked, 2–5-rayed (rarely some simple), 0.4–0.8 mm. |
blade narrowly oblanceolate, 1–3 mm wide, margins entire, ciliate proximally, trichomes to 0.7 mm, surfaces densely pubescent, trichomes short-stalked, 5–10-rayed, 0.08–0.25 mm. |
Cauline leaves | 10–30(–45), often concealing stem proximally; blade auricles 2–5(–6) mm, surfaces of distalmost leaves pubescent. |
4–9, not concealing stem; blade auricles 0.5–2 mm, surfaces of distalmost leaves pubescent. |
Racemes | 12–50(–70)-flowered, usually unbranched. |
8–25-flowered, usually unbranched. |
Flowers | ascending at anthesis; sepals pubescent; petals purple, 9–14 × 2–4 mm, glabrous or sparsely pubescent (trichomes abaxially); pollen ellipsoid. |
ascending at anthesis; sepals pubescent; petals lavender to purple, 4–5 × ca. 1 mm, glabrous; pollen spheroid. |
Fruiting pedicels | usually divaricate-ascending, rarely horizontal, gently recurved or straight, 8–22 mm, pubescent, trichomes subappressed, 2–4-rayed. |
ascending to divaricate-ascending, straight, 3–7 mm, pubescent, trichomes appressed, branched. |
Fruits | usually divaricate-ascending, rarely horizontal, not appressed to rachis, not secund, usually curved, edges parallel, (6–)8–13 cm × 1.5–2.2 mm; valves glabrous or trichomes relatively few, scattered; ovules 90–250 per ovary; style 0.01–0.5 mm. |
divaricate-ascending, not appressed to rachis, not secund, straight or curved, edges parallel, 4–6.2 cm × 1.2–1.8 mm; valves glabrous; ovules 48–68 per ovary; style 0.1–0.2 mm. |
Seeds | uniseriate or sub-biseriate, 1.5–1.7 × 1–1.2 mm; wing continuous, 0.1–0.2 mm wide. |
uniseriate, 1–1.5 × 0.8–1.2 mm; wing continuous, 0.1–0.15 mm wide. |
Boechera arcuata |
Boechera bodiensis |
|
Phenology | Flowering Mar–Jun. | Flowering Jul–Aug. |
Habitat | Rocky hillsides and cliffs in pine forests and chaparral | Loose soil, crevices of igneous rock |
Elevation | 300-1800 m (1000-5900 ft) | 2400-2900 m (7900-9500 ft) |
Distribution |
CA
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CA; NV |
Discussion | Although usually treated as a variety of Arabis (Boechera) sparsiflora (e.g., R. C. Rollins 1993), B. arcuata is easily distinguished from that species by having rachises and fruiting pedicels pubescent with subappressed, 2–4-rayed trichomes and a geographic range limited to southern and western California. By contrast, B. sparsiflora has rachises and fruiting pedicels with spreading, usually simple trichomes (sometimes glabrescent) and an allopatric distribution north and east of the Sierra Nevada. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Of conservation concern. In his original description, Rollins suggested that Boechera bodiensis is closely related to B. cobrensis and B. falcifructa. Subsequent studies (M. D. Windham and I. A. Al-Shehbaz, unpubl.) indicate that both B. bodiensis and B. falcifructa are apomictic hybrids containing one or more genomes derived from B. cobrensis. In the case of B. falcifructa, the second parent is clearly B. fernaldiana, but the second parent of B. bodiensis remains uncertain. Boechera bodiensis is most similar to B. falcifructa. The latter differs by having gently recurved fruiting pedicels 6–12 mm, 62–80 ovules per ovary, and pendulous fruits; it is known from Elko and Lander counties, Nevada. By contrast, B. bodiensis has straight fruiting pedicels 3–7 mm long, divaricate-ascending fruits, 48–68 ovules per ovary, and is known from Mono County, California, and Lyon and Mineral counties, Nevada. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 365. | FNA vol. 7, p. 367. |
Parent taxa | Brassicaceae > tribe Boechereae > Boechera | Brassicaceae > tribe Boechereae > Boechera |
Sibling taxa | ||
Synonyms | Streptanthus arcuatus, Arabis holboellii var. arcuata, Arabis maxima, Arabis sparsiflora var. arcuata | Arabis bodiensis |
Name authority | (Nuttall) Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 64. (2006) | (Rollins) Al-Shehbaz: Novon 13: 384. (2003) |
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