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Blue Mountain rockcress, hoary rock-cress, silver rockcress

Graham's rockcress, Graham's suncress

Habit Perennials; short-lived; sexual; caudex not woody. Biennials or perennials; short-lived; apomictic; caudex present or absent.
Stems

usually 1 per caudex branch, arising from center of rosette near ground surface, (1–)2–6.3 dm, densely pubescent proximally, trichomes short-stalked, 3–8-rayed, 0.1–0.3(–0.5) mm, similarly pubescent distally.

usually 1 per caudex branch, arising from center of rosette near ground surface, (1.2–)2–12 dm, glabrous or pubescent proximally, trichomes simple and sessile or subsessile, 2 or 3(–6)-rayed, to 1 mm, glabrous distally.

Basal leaves

blade oblanceolate to linear-oblanceolate, 1.5–5 mm wide, margins usually dentate, not ciliate, surfaces densely pubescent, trichomes short-stalked, 5–12-rayed, 0.05–0.2 mm.

blade oblanceolate, 1.5–10(–20) mm wide, margins entire or dentate, ciliate proximally, trichomes (simple), to 1 mm, surfaces sparsely to densely pubescent, trichomes sessile or subsessile, 2–4(–7)-rayed, 0.2–0.6 mm.

Cauline leaves

7–45(–65), concealing stem proximally;

blade auricles absent or 0.7–3 mm, surfaces of distalmost leaves pubescent.

(10–)13–52, often concealing stem proximally;

blade auricles 1–5 mm, surfaces of distalmost leaves glabrous.

Racemes

10–40(–64)-flowered, usually unbranched.

16–88-flowered, usually unbranched.

Flowers

ascending to descending at anthesis;

sepals pubescent;

petals white to lavender, 5–9 × 0.8–1.8 mm, glabrous;

pollen ellipsoid.

divaricate at anthesis;

sepals glabrous or pubescent;

petals usually white, rarely lavender, 5.5–8 × 1–2 mm, glabrous;

pollen spheroid.

Fruiting pedicels

pendent, recurved distal to horizontal to ascending base, 4–10 mm, pubescent, trichomes appressed, branched.

divaricate-ascending to descending, usually gently curved downward, rarely straight, 5–22(–30) mm, glabrous.

Fruits

closely pendent, rarely appressed to rachis, sometimes somewhat secund, usually straight, edges parallel, 3–6.5 cm × 1.9–2.2 mm;

valves pubescent throughout;

ovules 38–64 per ovary;

style 0.05–0.1 mm.

divaricate-ascending to pendent, not appressed to rachis, not secund, straight or slightly curved, edges parallel, 3.5–9 cm × 1–1.8 mm;

valves glabrous;

ovules 84–146 per ovary;

style 0.05–0.5 mm.

Seeds

uniseriate, 1.4–1.8 × 1–1.4 mm;

wing continuous, 0.1–0.3 mm wide.

uniseriate to sub-biseriate, 1–1.8 × 0.8–1.2 mm;

wing continuous, 0.1–0.25 mm wide.

2n

= 14.

= 21.

Boechera puberula

Boechera grahamii

Phenology Flowering Apr–Jul. Flowering May–Aug.
Habitat Ledges, rocky slopes, gravelly hillsides in sagebrush, pinyon-juniper, and mountain shrub communities Rocky slopes and sandy soil in prairies and open forests
Elevation 1300-2900 m (4300-9500 ft) 100-3200 m (300-10500 ft)
Distribution
from FNA
CA; NV; OR; UT
[WildflowerSearch map]
[BONAP county map]
from FNA
AK; CO; MI; MN; MT; ND; NY; SD; VT; WA; WI; WY; AB; BC; MB; NT; ON; QC; SK; YT
[WildflowerSearch map]
[BONAP county map]
Discussion

Boechera puberula is a diploid species that appears to intergrade with both B. retrofracta and B. subpinnatifida. The glabrous-fruited specimens discussed by R. C. Rollins (1993) represent apomictic hybrids with other species, primarily B. pendulocarpa.

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

Morphological evidence suggests that Boechera grahamii is an apomictic species that arose through hybridization between B. collinsii and B. stricta. Previous authors have assigned these specimens to Arabis (Boechera) divaricarpa (see M. D. Windham and I. A. Al-Shehbaz 2007b for detailed comparison); if these taxa are treated as conspecific, the name B. grahamii has priority.

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

Source FNA vol. 7, p. 399. FNA vol. 7, p. 382.
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. 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. 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
Synonyms Arabis puberula, Arabis arida, Arabis beckwithii, Arabis lignipes var. impar, Arabis sabulosa, Arabis subpinnatifida var. beckwithii, Arabis subpinnatifida var. impar, B. beckwithii Turritis grahamii, Arabis boivinii, Arabis bourgovii, Arabis confinis, Arabis confinis var. brachycarpa, Arabis dacotica, Arabis divaricarpa var. dacotica, Arabis divaricarpa var. hemicylindrica, Arabis divaricarpa var. stenocarpa, Arabis drummondii var. brachycarpa, Arabis holboellii var. brachycarpa, B. brachycarpa, Turritis brachycarpa
Name authority (Nuttall) Dorn: Brittonia, 55: 3. (2003) (Lehmann) Windham & Al-Shehbaz: Harvard Pap. Bot. 12: 241. (2007)
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