Boechera harrisonii |
Boechera gracilipes |
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Habit | Perennials; long-lived; (some-what cespitose); apomictic; caudex often woody. | Biennials or perennials; short-lived; sexual; caudex present or absent. |
Stems | usually 3–7 per caudex branch, arising from margin of rosette near ground surface, 0.5–2.5 dm, usually sparsely pubescent proximally, rarely glabrous, trichomes short-stalked, 2- or 3-rayed, 0.06–0.2 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 narrowly oblanceolate, 2–4 mm wide, margins entire or somewhat dentate, ciliate near petiole base, trichomes (simple), to 0.5 mm, surfaces sparsely pubescent, trichomes short-stalked, 2–5-rayed, 0.1–0.25 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 | 3–7, not concealing stem; blade auricles 0.5–1.5 mm, surfaces of distalmost leaves glabrous. |
30–65, often concealing stem proximally; blade auricles 0.8–3 mm, surfaces of distalmost leaves usually glabrous. |
Racemes | 5–12-flowered, usually unbranched. |
(12–)15–50-flowered, usually unbranched. |
Flowers | ascending at anthesis; sepals pubescent; petals lavender, 5–7.5 × 0.8–1.5 mm, glabrous; pollen 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, straight, 8–12 mm, glabrous. |
divaricate-ascending or horizontal, recurved, (15–)20–47 mm, glabrous. |
Fruits | usually divaricate-ascending, rarely nearly horizontal, not appressed to rachis, not secund, curved to straight, edges parallel, 3–4.7 cm × 1–1.5 mm; valves glabrous; ovules 64–86 per ovary; style 0.2–0.5 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, 1.1–1.3 × 0.8–1.1 mm; wing continuous, 0.08–0.1 mm wide. |
biseriate, 1.2–1.4 × 0.7–0.9 mm; wing continuous or distal, to 0.2 mm wide. |
Boechera harrisonii |
Boechera gracilipes |
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Phenology | Flowering May–Jun. | Flowering Apr–Jun. |
Habitat | Limestone and quartzite cliffs | Basalt, limestone, and sandy soils in ponderosa pine forests and pinyon-juniper woodlands |
Elevation | 1500-1600 m (4900-5200 ft) | 1700-2300 m (5600-7500 ft) |
Distribution |
UT |
AZ; NV; UT |
Discussion | Morphological evidence suggests that Boechera harrisonii is an apomictic species that arose through hybridization between B. microphylla and B. perennans (see M. D. Windham and I. A. Al-Shehbaz 2007 for detailed comparison). Boechera harrisonii is known only from Utah and Wasatch counties in north-central Utah. (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. 383. | FNA vol. 7, p. 381. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Arabis harrisonii, B. microphylla var. harrisonii | Arabis gracilipes, Arabis arcuata var. longipes, Arabis perennans var. longipes |
Name authority | (S. L. Welsh) Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 266. (2007) | (Greene) Dorn: Brittonia 55: 3. (2003) |
Web links |