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

Holboell's rock-cress, woodland rock-cress

Habit Perennials; long-lived; (often cespitose); sexual; caudex somewhat woody (usually without persistent leaf bases). Perennials; short-lived; apomictic; caudex 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, 2–8(–9.6) dm, densely pubescent proximally, trichomes simple and short-stalked, 2–4-rayed, to 1 mm, sparsely pubescent or 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 oblanceolate, 2–8(–11) mm wide, margins entire or denticulate, ciliate proximally, trichomes (simple), 0.5–1 mm, surfaces sparsely to densely pubescent, trichomes short-stalked, 2–4 (or 5)-rayed, 0.2–0.5 mm, these mixed with fewer simple ones.

Cauline leaves

5–10, not concealing stem;

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

7–33, often concealing stem proximally;

blade auricles 1–3 mm, surfaces of distalmost leaves sparsely pubescent or glabrous.

Racemes

10–25-flowered, often sparingly branched.

15–63-flowered, usually unbranched.

Flowers

divaricate-ascending at anthesis;

sepals pubescent;

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

pollen ellipsoid.

divaricate to pendent at anthesis;

sepals pubescent;

petals white to lavender, 5–6 × 1–1.5 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.

reflexed, abruptly recurved near base, otherwise straight, 4–12 mm, sparsely pubescent or glabrous, trichomes spreading, simple and 2-rayed.

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.

reflexed to closely pendent, not appressed to rachis, not secund, straight or curved, edges parallel, (4.5–)5.5–8.5 cm × 1.5–2 mm;

valves glabrous;

ovules 70–110 per ovary;

style 0.05–0.4 mm.

Seeds

uniseriate, 1.4–1.8 × 1–1.2 mm;

wing continuous, 0.25–0.5 mm wide.

uniseriate, 1.5–1.8 × 1.2–1.5 mm;

wing continuous, 0.15–0.3 mm wide.

2n

= 14.

Boechera cobrensis

Boechera pinetorum

Phenology Flowering May–Jun. Flowering May–Jul.
Habitat Sandy soil, usually under shelter of shrubs in semi-desert communities Rock outcrops and gravelly soil in meadows and open conifer forests
Elevation 1200-2800 m (3900-9200 ft) 1100-3200 m (3600-10500 ft)
Distribution
from FNA
CA; ID; NV; OR; WY
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; NV; OR
[WildflowerSearch map]
[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.)

Most authors (e.g., R. C. Rollins 1993; R. D. Dorn 2001; S. L. Welsh et al. 2003; N. H. Holmgren 2005b) have treated Boechera pinetorum as a variety of Arabis (Boechera) holboellii. Under this guise, the name has been applied to a vast array of plants collected throughout western North America. This includes a diversity of sexual diploids plus nearly every hybrid containing a genome from B. retrofracta. Based on re-examination of the type collection, we have adopted a much narrower concept of the species. Morphological evidence suggests that B. pinetorum is an apomictic triploid hybrid containing three different genomes, derived from B. rectissima, B. retrofracta, and B. sparsiflora. Plants closely resembling the type of B. pinetorum are confined to the northern Sierra Nevada and adjacent southern Cascades. The majority of collections previously associated with the epithet pinetorum represent B. pauciflora (see M. D. Windham and I. A. Al-Shehbaz 2007 for detailed comparison).

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

Source FNA vol. 7, p. 370. FNA vol. 7, p. 397.
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. 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
Synonyms Arabis cobrensis Arabis pinetorum, Arabis divaricarpa var. pinetorum, Arabis holboellii var. pinetorum, B. holboellii var. pinetorum
Name authority (M. E. Jones) Dorn: Vasc. Pl. Wyoming ed. 3, 375. (2001) (Tidestrom) Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 271. (2007)
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