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Hells Canyon rock-cress

Habit Perennials; short-lived; apomictic; caudex usually not woody. Perennials; short- to long-lived; apomictic or sexual; caudex often woody.
Stems

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.

1–4 per caudex branch, arising from margin of rosette near ground surface, 1–3 dm, glabrous throughout.

Basal leaves

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.

blade linear-oblanceolate to oblanceolate, 1–3(–5) mm wide, margins entire or minutely toothed, rarely ciliate near petiole base, trichomes (simple), to 0.8 mm, surfaces pubescent or glabrous, trichomes short-stalked, 3–6-rayed, 0.07–0.2 mm.

Cauline leaves

5–9, rarely concealing stem proximally;

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

4–15, not concealing stem;

blade auricles 0.5–2.5 mm, surfaces of distalmost leaves glabrous.

Racemes

5–13-flowered, usually unbranched.

12–40-flowered, usually unbranched.

Flowers

ascending at anthesis;

sepals pubescent;

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

pollen spheroid.

divaricate to pendent at anthesis;

sepals pubescent;

petals lavender, 5–6 × ca. 1 mm, glabrous;

pollen ellipsoid or spheroid.

Fruiting pedicels

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

reflexed, abruptly recurved near base, 4–8 mm, glabrous.

Fruits

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.

reflexed to closely pendent, usually appressed to rachis, often secund, straight, edges parallel, 0.3–0.42 cm × 1–1.5 mm;

valves glabrous;

ovules 46–60 per ovary.

Seeds

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

wing continuous, 0.05–0.12 mm wide.

uniseriate, 1–1.3 × 0.8–1 mm;

wing continuous, 0.05–0.1 mm wide.

Boechera saximontana

Boechera hastatula

Phenology Flowering Jun–Jul. Flowering Jun–Jul.
Habitat Rocky soil in sagebrush and open conifer forests Igneous rock outcrops
Elevation 2400-2900 m (7900-9500 ft) 1900-2100 m (6200-6900 ft)
Distribution
from FNA
ID; WY
[BONAP county map]
from FNA
OR
[BONAP county map]
Discussion

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.)

Of conservation concern.

Both sexual and apomictic collections of Boechera hastatula have been identified; further study is needed to determine whether they truly are conspecific. The species is known only from Baker and Wallowa counties.

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

Source FNA vol. 7, p. 404. FNA vol. 7, p. 383.
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. 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
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. 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
Synonyms Arabis microphylla var. saximontana, Arabis pendulocarpa var. saximontana, Arabis williamsii var. saximontana, B. williamsii var. saximontana Arabis hastatula
Name authority (Rollins) Windham & Al-Shehbaz: Harvard Pap. Bot. 12: 248. (2007) (Greene) Al-Shehbaz: Novon 13: 386. (2003)
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