Boechera shevockii |
Boechera pinetorum |
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Shevock's rockcress |
Holboell's rock-cress, woodland rock-cress |
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Habit | Perennials; long-lived; (pulvinate); sexual; caudex woody (with persistent, crowded leaf bases). | Perennials; short-lived; apomictic; caudex not woody. |
Stems | 1 per caudex branch, arising from center of rosette near ground surface, 0.5–1 dm, puberulent proximally, trichomes (scattered), simple, 0.02–0.1 mm, similarly pubescent distally. |
usually 1 per caudex branch, arising from center of rosette near ground surface, 2–8(–9.6) dm, densely pubescent proximally, trichomes simple and short-stalked, 2–4-rayed, to 1 mm, sparsely pubescent or glabrous distally. |
Basal leaves | blade oblong-oblanceolate, 1–2 mm wide, margins entire, ciliate distally, trichomes (simple), 0.02–0.1 mm, surfaces glabrous. |
blade oblanceolate, 2–8(–11) mm wide, margins entire or denticulate, ciliate proximally, trichomes (simple), 0.5–1 mm, surfaces sparsely to densely pubescent, trichomes short-stalked, 2–4 (or 5)-rayed, 0.2–0.5 mm, these mixed with fewer simple ones. |
Cauline leaves | 3–7, not concealing stem; blade auricles absent, surfaces of distalmost leaves glabrous. |
7–33, often concealing stem proximally; blade auricles 1–3 mm, surfaces of distalmost leaves sparsely pubescent or glabrous. |
Racemes | 4–7-flowered, unbranched. |
15–63-flowered, usually unbranched. |
Flowers | ascending at anthesis; sepals glabrous; petals lavender, 4–5 × 1–1.2 mm, glabrous; pollen ellipsoid. |
divaricate to pendent at anthesis; sepals pubescent; petals white to lavender, 5–6 × 1–1.5 mm, glabrous; pollen spheroid. |
Fruiting pedicels | ascending, straight, 5–9 mm, glabrous. |
reflexed, abruptly recurved near base, otherwise straight, 4–12 mm, sparsely pubescent or glabrous, trichomes spreading, simple and 2-rayed. |
Fruits | ascending, not appressed to rachis, not secund, straight, edges parallel, 2.5–3 cm × 1–1.5 mm; valves glabrous; ovules 30–34 per ovary; style ca. 0.5 mm. |
reflexed to closely pendent, not appressed to rachis, not secund, straight or curved, edges parallel, (4.5–)5.5–8.5 cm × 1.5–2 mm; valves glabrous; ovules 70–110 per ovary; style 0.05–0.4 mm. |
Seeds | uniseriate, ca. 1.2 × 0.8 mm; wing distal or continuous, ca. 0.1 mm wide. |
uniseriate, 1.5–1.8 × 1.2–1.5 mm; wing continuous, 0.15–0.3 mm wide. |
Boechera shevockii |
Boechera pinetorum |
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Phenology | Flowering Jun. | Flowering May–Jul. |
Habitat | Ledges of rock outcrops | Rock outcrops and gravelly soil in meadows and open conifer forests |
Elevation | ca. 2500 m (ca. 8200 ft) | 1100-3200 m (3600-10500 ft) |
Distribution |
CA |
CA; NV; OR
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Discussion | Boechera shevockii is a close relative of B. davidsonii, from which it is readily distinguished by having puberulent (versus glabrous) stems, shorter (4–5 versus 6–10 mm) petals, and much shorter (5–7 versus 30–80 mm) basal leaves. It is known only from the type specimen, from the southern Sierra Nevada in Tulare County. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Most authors (e.g., R. C. Rollins 1993; R. D. Dorn 2001; S. L. Welsh et al. 2003; N. H. Holmgren 2005b) have treated Boechera pinetorum as a variety of Arabis (Boechera) holboellii. Under this guise, the name has been applied to a vast array of plants collected throughout western North America. This includes a diversity of sexual diploids plus nearly every hybrid containing a genome from B. retrofracta. Based on re-examination of the type collection, we have adopted a much narrower concept of the species. Morphological evidence suggests that B. pinetorum is an apomictic triploid hybrid containing three different genomes, derived from B. rectissima, B. retrofracta, and B. sparsiflora. Plants closely resembling the type of B. pinetorum are confined to the northern Sierra Nevada and adjacent southern Cascades. The majority of collections previously associated with the epithet pinetorum represent B. pauciflora (see M. D. Windham and I. A. Al-Shehbaz 2007 for detailed comparison). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 406. | FNA vol. 7, p. 397. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Arabis pinetorum, Arabis divaricarpa var. pinetorum, Arabis holboellii var. pinetorum, B. holboellii var. pinetorum | |
Name authority | Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 82. (2006) | (Tidestrom) Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 271. (2007) |
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