Boechera lemmonii |
Boechera gracilipes |
|
---|---|---|
Lemmon's rock-cress, Lemmon's suncress, wind-blown suncress |
|
|
Habit | Perennials; long-lived; (somewhat cespitose); sexual or apomictic; caudex woody. | Biennials or perennials; short-lived; sexual; caudex present or absent. |
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 1 per caudex branch, arising from center of rosette near ground surface, rarely arising laterally proximal to sterile shoots, 2.5–8.5 dm, densely pubescent proximally, trichomes simple or spurred, 0.9–1.5 mm, 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 oblanceolate, 5–12 mm wide, margins shallowly dentate, sometimes ciliate near petiole base, surfaces sparsely to densely pubescent, trichomes short- to long-stalked, 2- or 3-rayed, usually 0.3–0.6 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. |
30–65, often concealing stem proximally; blade auricles 0.8–3 mm, surfaces of distalmost leaves usually glabrous. |
Racemes | 3–12(–17)-flowered, usually unbranched. |
(12–)15–50-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. |
ascending at anthesis; sepals pubescent; petals white to pale lavender, 6–9 × 0.6–1 mm; valves glabrous; pollen ellipsoid. |
Fruiting pedicels | divaricate-ascending to slightly descending, usually slightly recurved, rarely straight, 2–6 mm, glabrous or sparsely pubescent, trichomes appressed, branched. |
divaricate-ascending or horizontal, recurved, (15–)20–47 mm, glabrous. |
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, curved, edges parallel, (2.5–)3–7.5 cm × 1.5–2.8 mm, glabrous; ovules 130–210 per ovary; style 0.2–0.5 mm. |
Seeds | uniseriate, 1.3–2 × 1–1.5 mm; wing continuous, 0.1–0.5 mm wide. |
biseriate, 1.2–1.4 × 0.7–0.9 mm; wing continuous or distal, to 0.2 mm wide. |
2n | = 14. |
|
Boechera lemmonii |
Boechera gracilipes |
|
Phenology | Flowering Jun–Aug. | Flowering Apr–Jun. |
Habitat | Cliffs, talus slopes, and gravelly soil in alpine and subalpine habitats | Basalt, limestone, and sandy soils in ponderosa pine forests 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
|
AZ; NV; UT |
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.) |
Fruiting pedicel length, considered diagnostic by R. C. Rollins (1993) and N. H. Holmgren (2005b), occasionally fails to separate Boechera gracilipes from the closely-related B. fendleri. The two are consistently distinguished by trichome characters. In B. gracilipes, basal leaves usually lack prominent cilia and surfaces are persistently pubescent with at least some 3-rayed trichomes. Also, stems are rather densely pilose proximally, with the largest trichomes more than 0.9 mm. By contrast, basal leaves of B. fendleri always have prominent cilia, surfaces are often glabrescent, and 3-rayed trichomes usually are rare or absent. Stems of the latter are proximally hirsute to hispid, with the largest trichomes less than 0.9 mm. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 388. | FNA vol. 7, p. 381. |
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 gracilipes, Arabis arcuata var. longipes, Arabis perennans var. longipes |
Name authority | (S. Watson) W. A. Weber: Phytologia 51: 370. (1982) | (Greene) Dorn: Brittonia 55: 3. (2003) |
Web links |
|