Boechera falcatoria |
Boechera spatifolia |
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spoonleaf rockcress |
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Habit | Perennials; short- to long-lived; apomictic; caudex sometimes woody. | Perennials; short- to long-lived; sexual; caudex usually not woody (rarely with persistent, crowded leaf bases). |
Stems | usually 2–7 per caudex branch, arising from margin of rosette near ground surface, 0.5–2(–3) dm, densely pubescent proximally, trichomes simple and stalked, 2-rayed, 0.3–0.8 mm, glabrous distally. |
simple or few to several per caudex branch, arising from center of rosette near ground surface, 1.5–3.5(–5) dm, densely pubescent proximally, trichomes simple mixed with short-stalked ones, 2-rayed, 0.3–0.7 mm. |
Basal leaves | blade narrowly oblanceolate, 1–3 mm wide, margins entire, ciliate, trichomes to 1 mm, surfaces pubescent, trichomes stalked, 2–4-rayed, 0.3–0.8 mm. |
blade narrowly oblanceolate, 1.5–3(–4) mm wide, margins entire, strongly ciliate at least along petiole, trichomes (simple), to 1 mm, surfaces glabrous or sparsely pubescent, trichomes simple and short-stalked, 2-rayed, 0.3–0.7 mm. |
Cauline leaves | 3–7(–10), not concealing stem; blade auricles 0.2–1 mm, surfaces of distalmost leaves glabrous. |
5–15(–20), often concealing stem proximally; blade auricles 0.5–1.5 mm, surfaces of distalmost leaves usually glabrous. |
Racemes | 6–15-flowered, unbranched. |
10–30-flowered, usually unbranched. |
Flowers | ascending at anthesis; sepals pubescent; petals white or lavender, 5–7 × 1.5–2.5 mm, glabrous; pollen spheroid. |
divaricate-ascending at anthesis; sepals pubescent; petals usually white, rarely pale lavender, 3–3.7(–4) × 0.5–0.8 mm, glabrous; pollen ellipsoid. |
Fruiting pedicels | horizontal to divaricate-ascending, straight, 3–9 mm, glabrous. |
horizontal or slightly descending, curved or angled downward, 6–10(–15) mm, usually glabrous, rarely sparsely pubescent, trichomes spreading, simple. |
Fruits | horizontal to divaricate-ascending, not appressed to rachis, not secund, usually strongly curved, edges parallel, 3.5–6.5 cm × 1.7–2 mm; valves glabrous; ovules 50–84 per ovary; style 0.05–0.5 mm. |
pendent, not appressed to rachis, rarely slightly secund, straight or gently curved, edges parallel, 3.3–5.7 cm × 1.2–1.8 mm; valves glabrous; ovules 90–126 per ovary; style 0.1–0.4 mm. |
Seeds | uniseriate, 1.5–2 × 1.1–1.5 mm; wing continuous, 0.1–0.2 mm wide. |
biseriate, 0.7–0.9 × 0.5–0.6 mm; wing distal or, sometimes, absent, 0.05–0.1 mm wide. |
2n | = 14. |
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Boechera falcatoria |
Boechera spatifolia |
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Phenology | Flowering May–Jun. | Flowering May–Aug. |
Habitat | Rock outcrops and gravelly soil in sagebrush and mountain shrub communities | Rocky slopes and gravelly soil in sagebrush, pinyon-juniper woodlands, open conifer forests and subalpine meadows |
Elevation | 2000-2200 m (6600-7200 ft) | 1800-2800 m (5900-9200 ft) |
Distribution |
UT |
CO; NM
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Discussion | Of conservation concern. Although the exact parentage of Boechera falcatoria, an apomictic hybrid, remains in doubt, it is virtually certain that B. cusickii contributed at least one genome. Boechera falcatoria has been confused with both B. pendulina and B. perennans, but is amply distinct from both (see M. D. Windham and I. A. Al-Shehbaz 2007 for detailed comparison). Despite the proximity of the type locality to both Idaho and Nevada, the species is known only from northwestern Box Elder County. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Boechera spatifolia is a sexual diploid that usually has been treated as a variety of Arabis (Boechera) fendleri but appears to be sufficiently distinct to warrant recognition at species level (see M. D. Windham and I. A. Al-Shehbaz 2006 for detailed comparison). There is little geographic overlap between the two, with B. spatifolia confined to the mountains of central Colorado and north-central New Mexico and B. fendleri ranging from western New Mexico and the Four Corners region through northern Arizona to southern Nevada. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 376. | FNA vol. 7, p. 408. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Arabis falcatoria | Arabis spatifolia, Arabis fendleri var. spatifolia, B. fendleri subsp. spatifolia, B. fendleri var. spatifolia |
Name authority | (Rollins) Dorn: Brittonia 55: 3. (2003) | (Rydberg) Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 84. (2006) |
Web links |