Boechera collinsii |
Brassicaceae tribe Boechereae |
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collin's suncress, Collins' rockcress |
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Habit | Perennials; usually short-lived; sexual; caudex not woody. | Perennials or, rarely, biennials; eglandular. |
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. |
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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. |
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Cauline leaves | (8–)15–40, concealing stem proximally; blade auricles 1–3 mm, surfaces of distalmost leaves usually sparsely pubescent. |
(sometimes absent); petiolate, subsessile, or sessile; blade base auriculate or not, margins usually entire or dentate, rarely pinnatifid. |
Trichomes | often short-stalked, sessile, or subsessile, usually forked or dendritic, rarely malpighiaceous, sometimes simple or absent. |
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Racemes | (15–)30–90-flowered, usually unbranched. |
ebracteate, often elongated in fruit. |
Flowers | descending to pendent at anthesis; sepals pubescent; petals usually white, rarely lavender, 4–6 × 0.8–1.5 mm, glabrous; pollen ellipsoid. |
actinomorphic; sepals erect, ascending, or spreading, lateral pair usually not saccate basally; petals white, yellowish, pink, lavender, or purple, claw present, often indistinct; filaments unappendaged, not winged; pollen 3-colpate. |
Fruiting pedicels | reflexed, abruptly recurved at base, otherwise straight, 4–13 mm, glabrous or sparsely pubescent, trichomes usually simple. |
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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. |
usually siliques, rarely silicles, dehiscent, unsegmented, usually latiseptate, rarely terete or slightly angustiseptate; ovules [2–]4–250 per ovary; style usually distinct, rarely obsolete; stigma usually entire, rarely 2-lobed. |
Seeds | uniseriate, 1–1.4 × 0.8–1 mm; wing continuous (rarely absent), to 0.1 mm wide. |
biseriate, sub-biseriate, uniseriate, or, rarely, aseriate; cotyledons accumbent or incumbent. |
2n | = 14. |
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Boechera collinsii |
Brassicaceae tribe Boechereae |
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Phenology | Flowering May–Jun. | |
Habitat | Rocky and gravelly hillsides, prairies, open woods, floodplains | |
Elevation | 600-1400 m (2000-4600 ft) | |
Distribution |
ID; MN; MT; ND; NE; SD; WY; AB; MB; QC; SK
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North America; Asia (Russian Far East) |
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.) |
Genera 7, species 119 (7 genera, 117 species in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 370. | FNA vol. 7, p. 347. |
Parent taxa | Brassicaceae > tribe Boechereae > Boechera | Brassicaceae |
Sibling taxa | ||
Subordinate taxa | ||
Synonyms | Arabis collinsii, Arabis holboellii var. collinsii, Arabis retrofracta var. collinsii | |
Name authority | (Fernald) Á. Löve & D. Löve: Taxon 31: 125. (1982) | Al-Shehbaz: Pl. Syst Evol. 259: 111. (2006) |
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