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collin's suncress, Collins' rockcress

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.

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.

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.

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.

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.

Boechera collinsii

Brassicaceae tribe Boechereae

Phenology Flowering May–Jun.
Habitat Rocky and gravelly hillsides, prairies, open woods, floodplains
Elevation 600-1400 m (2000-4600 ft)
Distribution
from FNA
ID; MN; MT; ND; NE; SD; WY; AB; MB; QC; SK
[WildflowerSearch map]
[BONAP county map]
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
B. acutina, B. arcuata, B. atrorubens, B. bodiensis, B. breweri, B. burkii, B. calderi, B. californica, B. canadensis, B. cascadensis, B. cobrensis, B. consanguinea, B. constancei, B. covillei, B. crandallii, B. cusickii, B. davidsonii, B. dentata, B. depauperata, B. dispar, B. divaricarpa, B. drepanoloba, B. duchesnensis, B. elkoensis, B. evadens, B. falcatoria, B. falcifructa, B. fecunda, B. fendleri, B. fernaldiana, B. formosa, B. fructicosa, B. glareosa, B. glaucovalvula, B. goodrichii, B. gracilenta, B. gracilipes, B. grahamii, B. gunnisoniana, B. harrisonii, B. hastatula, B. hoffmannii, B. holboellii, B. horizontalis, B. howellii, B. inyoensis, B. johnstonii, B. koehleri, B. laevigata, B. languida, B. lasiocarpa, B. lemmonii, B. lignifera, B. lincolnensis, B. lyallii, B. macounii, B. microphylla, B. missouriensis, B. nevadensis, B. ophira, B. oxylobula, B. paddoensis, B. pallidifolia, B. parishii, B. pauciflora, B. paupercula, B. peirsonii, B. pendulina, B. pendulocarpa, B. perennans, B. perstellata, B. pinetorum, B. pinzliae, B. platysperma, B. polyantha, B. porphyrea, B. pratincola, B. puberula, B. pulchra, B. pusilla, B. pygmaea, B. quebecensis, B. rectissima, B. repanda, B. retrofracta, B. rigidissima, B. rollei, B. rollinsiorum, B. rubicundula, B. saximontana, B. schistacea, B. serotina, B. serpenticola, B. shevockii, B. shockleyi, B. sparsiflora, B. spatifolia, B. stricta, B. subpinnatifida, B. suffrutescens, B. texana, B. tiehmii, B. tularensis, B. ultra-alsa, B. villosa, B. williamsii, B. xylopoda, B. yorkii
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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