Boechera collinsii |
Boechera glaucovalvula |
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collin's suncress, Collins' rockcress |
bluepod rockcress |
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Habit | Perennials; usually short-lived; sexual; caudex not woody. | Perennials; short- to long-lived; sexual; caudex usually not woody. |
Stems | usually 1 per caudex branch, arising from center of rosette near ground surface, (1.5–)2.5–8 dm, densely pubescent proximally, trichomes simple and short-stalked, 2-rayed, to 1 mm, sparsely pubescent or glabrous distally. |
usually 1 per caudex branch, arising from center of rosette near ground surface, (0.6–)1–4.5 dm, densely pubescent proximally, trichomes short-stalked, 4–8-rayed, 0.1–0.4 mm, similarly pubescent distally. |
Basal leaves | blade oblanceolate, 1–7 mm wide, margins entire or dentate, ciliate along petiole, trichomes (simple), to 0.7 mm, surfaces moderately to densely pubescent, trichomes short-stalked, 5–8-rayed, 0.15–0.4 mm. |
blade linear to linear-oblanceolate, 2–4(–6) mm wide, margins entire, usually ciliate at petiole base, trichomes (simple or spurred), to 1.5 mm, surfaces densely pubescent, trichomes short-stalked, 4–8-rayed, 0.1–0.4 mm. |
Cauline leaves | (8–)15–40, concealing stem proximally; blade auricles 1–3 mm, surfaces of distalmost leaves usually sparsely pubescent. |
6–10, not concealing stem; blade auricles absent, surfaces of distalmost leaves densely pubescent. |
Racemes | (15–)30–90-flowered, usually unbranched. |
(5–)10–25-flowered, usually unbranched. |
Flowers | descending to pendent at anthesis; sepals pubescent; petals usually white, rarely lavender, 4–6 × 0.8–1.5 mm, glabrous; pollen ellipsoid. |
divaricate at anthesis; sepals pubescent; petals light purple to lavender, 6–9 × 1.5–2.5 mm, glabrous; pollen ellipsoid. |
Fruiting pedicels | reflexed, abruptly recurved at base, otherwise straight, 4–13 mm, glabrous or sparsely pubescent, trichomes usually simple. |
reflexed, strongly curved at base, 2–10 mm, pubescent, trichomes appressed, branched. |
Fruits | strongly reflexed, usually appressed to rachis, rarely somewhat secund, straight, edges parallel, 3.5–6 cm × 0.9–1.5 mm; valves glabrous; ovules 70–126 per ovary; style 0.2–0.5 mm. |
strongly reflexed, sometimes appressed to rachis, often secund, straight, edges parallel, (1.8–)2.5–4.5 cm × 5–8 mm; valves glabrous; ovules 24–62 per ovary; style 0.2–0.6 mm. |
Seeds | uniseriate, 1–1.4 × 0.8–1 mm; wing continuous (rarely absent), to 0.1 mm wide. |
biseriate, 5–6 × 4–5 mm; wing continuous, 1.8–2.5 mm wide. |
2n | = 14. |
= 14. |
Boechera collinsii |
Boechera glaucovalvula |
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Phenology | Flowering May–Jun. | Flowering Mar–Apr. |
Habitat | Rocky and gravelly hillsides, prairies, open woods, floodplains | Rocky slopes and gravelly soil, usually under shelter of desert shrubs |
Elevation | 600-1400 m (2000-4600 ft) | 600-1600 m (2000-5200 ft) |
Distribution |
ID; MN; MT; ND; NE; SD; WY; AB; MB; QC; SK
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CA; NV
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Discussion | Though often treated as a variety of Arabis (Boechera) holboellii (e.g., R. C. Rollins 1993; G. A. Mulligan 1996), B. collinsii is easily distinguished from that species by having simple and 2-rayed (versus 4–8-rayed) trichomes proximally on stems, and narrower (0.9–1.5 versus 2–2.5 mm) usually non-secund fruits. The two taxa also show allopatric distributions, with B. collinsii found on the North American continent (usually east of the Rocky Mountains) and B. holboellii apparently confined to Greenland. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Boechera glaucovalvula, a distinctive sexual diploid that has the widest fruits in the genus, is known from Inyo, Mono, Riverside, and San Bernardino counties, California, and Clark and Nye counties, Nevada. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 370. | FNA vol. 7, p. 380. |
Parent taxa | Brassicaceae > tribe Boechereae > Boechera | Brassicaceae > tribe Boechereae > Boechera |
Sibling taxa | ||
Synonyms | Arabis collinsii, Arabis holboellii var. collinsii, Arabis retrofracta var. collinsii | Arabis glaucovalvula |
Name authority | (Fernald) Á. Löve & D. Löve: Taxon 31: 125. (1982) | (M. E. Jones) Al-Shehbaz: Novon 13: 385. (2003) |
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