Boechera lemmonii |
Boechera lignifera |
|
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Lemmon's rock-cress, Lemmon's suncress, wind-blown suncress |
desert rockcress |
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Habit | Perennials; long-lived; (somewhat cespitose); sexual or apomictic; caudex woody. | Perennials; short- to long-lived; apomictic or sexual; caudex usually woody. |
Stems | usually 1 per caudex branch, arising from center of rosette near ground surface, or arising laterally proximal to sterile shoots, 0.5–2(–2.5) dm, glabrous or sparsely pubescent proximally, trichomes short-stalked, 2–6-rayed, 0.1–0.2 mm, glabrous distally. |
usually 2–5 per caudex branch, arising laterally proximal to sterile shoots, often elevated on woody base, 1.2–4(–5) dm, densely pubescent proximally, trichomes short-stalked, 4–7-rayed, 0.1–0.3 mm, sparsely pubescent or glabrous distally. |
Basal leaves | blade oblanceolate to obovate, 1.5–5 mm wide, margins usually entire, rarely slightly dentate, ciliate along petiole, surfaces densely to sparsely pubescent, trichomes short-stalked, 3–9-rayed, 0.1–0.2 mm. |
blade narrowly oblanceolate, 2–5(–8) mm wide, margins entire, rarely ciliate near petiole base, trichomes (simple or spurred), to 1 mm, surfaces densely pubescent, trichomes short-stalked, 3–7-rayed, 0.05–0.3 mm. |
Cauline leaves | 2–8(–12), not concealing stem; blade auricles absent or 0.1–0.5 mm, surfaces of distalmost leaves glabrous or sparsely pubescent. |
4–12(–17), rarely concealing stem proximally; blade auricles 0.5–2 mm, surfaces of distalmost leaves sparsely pubescent. |
Racemes | 3–12(–17)-flowered, usually unbranched. |
6–15(–25)-flowered, usually unbranched. |
Flowers | divaricate-ascending at anthesis; sepals glabrous or sparsely pubescent; petals purple to lavender, 3.5–6 × 1–1.5 mm; pollen ellipsoid or spheroid. |
divaricate-ascending at anthesis; sepals pubescent; petals whitish (often aging pale lavender), 5–7 × 1–1.5 mm, glabrous; pollen ellipsoid or spheroid. |
Fruiting pedicels | divaricate-ascending to slightly descending, usually slightly recurved, rarely straight, 2–6 mm, glabrous or sparsely pubescent, trichomes appressed, branched. |
slightly descending, gently recurved, 5–16 mm, glabrous or sparsely pubescent, trichomes appressed, branched. |
Fruits | divaricate-ascending to slightly descending, not appressed to rachis, secund, straight or curved, edges parallel, (1.6–) 2–4.4 cm × 1.6–2.3 mm; valves glabrous; ovules 28 40(–44) per ovary; style 0.1–0.2 mm. |
widely pendent, not appressed to rachis, not secund, usually curved, edges parallel, 2.5–5.6 cm × 1.2–2 mm; valves glabrous; ovules 48–74 per ovary; style 0.1–0.2 mm. |
Seeds | uniseriate, 1.3–2 × 1–1.5 mm; wing continuous, 0.1–0.5 mm wide. |
uniseriate, 1–1.3 × 0.8–1 mm; wing often continuous, 0.1–0.15 mm wide. |
2n | = 14. |
= 14. |
Boechera lemmonii |
Boechera lignifera |
|
Phenology | Flowering Jun–Aug. | Flowering Apr–May. |
Habitat | Cliffs, talus slopes, and gravelly soil in alpine and subalpine habitats | Rocky slopes and sandy soil in sagebrush and pinyon-juniper woodlands |
Elevation | 2100-4400 m (6900-14400 ft) | 1700-2300 m (5600-7500 ft) |
Distribution |
AK; CA; CO; ID; MT; NV; OR; UT; WA; WY; AB; BC; YT
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AZ; CO; ID; NM; UT; WY
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Discussion | Boechera lemmonii is easily recognized by its combination of secund fruits, mat-forming habit, purplish sepals, and obovate-oblanceolate cauline leaves. Both sexual and apomictic collections are known; further study is needed to determine whether they truly are conspecific. The taxa traditionally treated as Arabis (Boechera) lemmonii vars. depauperata, drepanoloba, and paddoensis are apomictic hybrids here recognized as distinct species (see M. D. Windham and I. A. Al-Shehbaz 2007 for detailed comparison). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Boechera lignifera is commonly found on stabilized sand dunes. The related B. cobrensis often is found in similar habitats, and the two species can be difficult to distinguish where their ranges overlap in Idaho and Wyoming. It is possible that B. cobrensis was involved in the origin of some apomictic populations currently assigned to B. lignifera. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 388. | FNA vol. 7, p. 388. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Arabis lemmonii, Arabis bracteolata, Arabis canescens var. latifolia, Arabis codyi, Arabis egglestonii, Arabis kennedyi, Arabis latifolia, Arabis oreocallis, Arabis polyclada, Arabis semisepulta | Arabis lignifera |
Name authority | (S. Watson) W. A. Weber: Phytologia 51: 370. (1982) | (A. Nelson) W. A. Weber: Phytologia 51: 370. (1982) |
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