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cobre rock-cress, Masonic rock-cress, sagebrush rockcress

Habit Perennials; long-lived; (often cespitose); sexual; caudex somewhat woody (usually without persistent leaf bases). Perennials; short-lived; apomictic; caudex usually not woody.
Stems

usually 1 per caudex branch, arising from center of rosette near ground surface, (1.2–)2.5–6 dm, densely pubescent proximally, trichomes short-stalked, 4–10-rayed, 0.1–0.2 mm, sparsely pubescent or glabrous distally.

usually 1 per caudex branch, arising from center of rosette near ground surface, 0.7–3 dm, densely pubescent proximally, trichomes short-stalked, 2–6-rayed, 0.06–0.25 mm, glabrous distally.

Basal leaves

blade linear to narrowly oblanceolate, 1–4 mm wide, margins entire, ciliate near petiole base, trichomes (simple), to 0.6 mm, surfaces densely pubescent, trichomes short-stalked, 4–10-rayed, 0.1–0.2 mm.

blade narrowly oblanceolate, 1–3 mm wide, margins entire, ciliate near petiole base, trichomes (simple and spurred), to 0.4 mm, surfaces sparsely to densely pubescent, trichomes short-stalked, 4–8-rayed, 0.04–0.15 mm.

Cauline leaves

5–10, not concealing stem;

blade auricles 1–1.5 mm, surfaces of distalmost leaves usually sparsely pubescent.

5–9, rarely concealing stem proximally;

blade auricles to 0.3–1 mm, surfaces of distalmost leaves glabrous.

Racemes

10–25-flowered, often sparingly branched.

5–13-flowered, usually unbranched.

Flowers

divaricate-ascending at anthesis;

sepals pubescent;

petals white to lavender, 3.5–6 × 0.7–1 mm, glabrous;

pollen ellipsoid.

ascending at anthesis;

sepals pubescent;

petals lavender, 4–5 × 0.5–0.8 mm, glabrous;

pollen spheroid.

Fruiting pedicels

divaricate-ascending to horizontal, often straight proximally, usually strongly recurved or reflexed distally, 4–17 mm, usually pubescent, rarely glabrous, trichomes appressed, branched.

divaricate-ascending, straight, 3–8 mm, glabrous.

Fruits

pendent, not appressed to rachis, not secund, straight or slightly curved, edges parallel, 2.5–5.5 cm × 1.7–2.5 mm;

valves glabrous;

ovules 34–64 per ovary;

style 0.05–0.2 mm.

divaricate-ascending, not appressed to rachis, not secund, straight, edges parallel, (2.5–)3–4.7 cm × 1.2–1.7 mm;

valves glabrous;

ovules 78–112 per ovary;

style 0.1–0.5 mm.

Seeds

uniseriate, 1.4–1.8 × 1–1.2 mm;

wing continuous, 0.25–0.5 mm wide.

uniseriate to sub-biseriate, 1.1–1.4 × 0.7–0.9 mm;

wing continuous, 0.05–0.12 mm wide.

2n

= 14.

Boechera cobrensis

Boechera saximontana

Phenology Flowering May–Jun. Flowering Jun–Jul.
Habitat Sandy soil, usually under shelter of shrubs in semi-desert communities Rocky soil in sagebrush and open conifer forests
Elevation 1200-2800 m (3900-9200 ft) 2400-2900 m (7900-9500 ft)
Distribution
from FNA
CA; ID; NV; OR; WY
[WildflowerSearch map]
[BONAP county map]
from FNA
ID; WY
[BONAP county map]
Discussion

Boechera cobrensis is a sexual diploid commonly found on stabilized sand dunes. The related B. lignifera often is found in similar habitats, and the two species can be difficult to distinguish where their ranges overlap in Idaho and Wyoming. It is possible that B. cobrensis was involved in the origin of some apomictic populations currently assigned to B. lignifera.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Boechera saximontana is an apomictic taxon that has been treated as a variety of either Arabis microphylla (R. C. Rollins 1941) or A. (Boechera) williamsii (Rollins 1993; R. D. Dorn 2001). It is easily distinguished from typical collections of those species (see M. D. Windham and I. A. Al-Shehbaz 2007b for detailed comparison), but it is likely that one (or both) were involved in its hybrid origin. It is known from Blaine, Custer, and Lemhi counties in Idaho, and Big Horn and Fremont counties in Wyoming.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 7, p. 370. FNA vol. 7, p. 404.
Parent taxa Brassicaceae > tribe Boechereae > Boechera Brassicaceae > tribe Boechereae > Boechera
Sibling taxa
B. acutina, B. arcuata, B. atrorubens, B. bodiensis, B. breweri, B. burkii, B. calderi, B. californica, B. canadensis, B. cascadensis, B. collinsii, 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
B. acutina, B. arcuata, B. atrorubens, B. bodiensis, B. breweri, B. burkii, B. calderi, B. californica, B. canadensis, B. cascadensis, B. cobrensis, B. collinsii, 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. 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
Synonyms Arabis cobrensis Arabis microphylla var. saximontana, Arabis pendulocarpa var. saximontana, Arabis williamsii var. saximontana, B. williamsii var. saximontana
Name authority (M. E. Jones) Dorn: Vasc. Pl. Wyoming ed. 3, 375. (2001) (Rollins) Windham & Al-Shehbaz: Harvard Pap. Bot. 12: 248. (2007)
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