Boechera arcuata |
Boechera ophira |
|
---|---|---|
arching rockcress, elegant rockcress |
|
|
Habit | Perennials; usually long-lived; sexual; caudex often woody (well-developed). | Perennials; long-lived; (cespitose); sexual; caudex often 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, 0.4–1.4 dm, densely pubescent proximally, trichomes short-stalked, 2- or 3-rayed, 0.2–0.3 mm, sparsely to moderately pubescent 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 to linear, 0.8–1.8 mm wide, margins entire, ciliate along petiole, trichomes (simple), to 0.8 mm, surfaces densely pubescent, trichomes short-stalked, 2- or 3-rayed, 0.2–0.3 mm. |
Cauline leaves | 10–30(–45), often concealing stem proximally; blade auricles 2–5(–6) mm, surfaces of distalmost leaves pubescent. |
6–10, somewhat concealing stem proximally; blade auricles to 0.5 mm, surfaces of distalmost leaves pubescent. |
Racemes | 12–50(–70)-flowered, usually unbranched. |
6–15-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 purplish, 4–5 × 1–1.8 mm, glabrous; pollen ellipsoid. |
Fruiting pedicels | usually divaricate-ascending, rarely horizontal, gently recurved or straight, 8–22 mm, pubescent, trichomes subappressed, 2–4-rayed. |
ascending, straight, 3–8 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. |
suberect or ascending, sometimes appressed to rachis, not secund, straight, edges parallel, 2.5–4 cm × 1.2–1.8 mm; valves glabrous; ovules 50–60 per ovary; style 0.05–0.1 mm. |
Seeds | uniseriate or sub-biseriate, 1.5–1.7 × 1–1.2 mm; wing continuous, 0.1–0.2 mm wide. |
uniseriate, 1.2–1.8 × 1–1.5 mm; wing continuous, 0.1–0.2 mm wide. |
Boechera arcuata |
Boechera ophira |
|
Phenology | Flowering Mar–Jun. | Flowering May–Jun. |
Habitat | Rocky hillsides and cliffs in pine forests and chaparral | Rocky slopes, gravelly soil in subalpine meadows |
Elevation | 300-1800 m (1000-5900 ft) | 3000-3200 m (9800-10500 ft) |
Distribution |
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. Boechera ophira is known only from the Toiyabe Range in west-central Nevada. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 365. | FNA vol. 7, p. 391. |
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 ophira |
Name authority | (Nuttall) Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 64. (2006) | (Rollins) Al-Shehbaz: Novon 13: 387. (2003) |
Web links |
|