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arching rockcress, elegant rockcress

serpentine rockcress

Habit Perennials; usually long-lived; sexual; caudex often woody (well-developed). Perennials; long-lived; (cespitose); sexual; caudex woody.
Stems

usually 1 per caudex branch, arising from center of rosette, elevated on woody base or from ground surface, (2–)3–8 dm, densely pubescent proximally, trichomes short-stalked, 2-rayed and simple, to 1 mm, pubescent distally.

usually 1 per caudex branch, arising from center of rosette near ground surface, 0.5–1.8 dm, densely pubescent proximally, trichomes short-stalked, 5–8-rayed, 0.1–0.2, sparsely to moderately pubescent distally.

Basal leaves

blade linear to oblanceolate, 2–7(–12) mm wide, margins usually entire, rarely denticulate, ciliate along petiole, trichomes to 1.5 mm, surfaces densely pubescent, trichomes usually short-stalked, 2–5-rayed (rarely some simple), 0.4–0.8 mm.

blade narrowly oblanceolate, 1–2 mm wide, margins entire, ciliate along petiole, trichomes (branched), to 0.5 mm, surfaces densely pubescent, trichomes short-stalked, 5–8-rayed, 0.1–0.2 mm.

Cauline leaves

10–30(–45), often concealing stem proximally;

blade auricles 2–5(–6) mm, surfaces of distalmost leaves pubescent.

4–14, rarely concealing stem proximally;

blade auricles 0.1–0.5 mm, surfaces of distalmost leaves densely pubescent.

Racemes

12–50(–70)-flowered, usually unbranched.

10–20-flowered, unbranched.

Flowers

ascending at anthesis;

sepals pubescent;

petals purple, 9–14 × 2–4 mm, glabrous or sparsely pubescent (trichomes abaxially);

pollen ellipsoid.

ascending at anthesis;

sepals pubescent;

petals purple, 6–8 × 1.5–2.5 mm, glabrous;

pollen ellipsoid.

Fruiting pedicels

usually divaricate-ascending, rarely horizontal, gently recurved or straight, 8–22 mm, pubescent, trichomes subappressed, 2–4-rayed.

divaricate-descending or horizontal, nearly straight, 3–7 mm, pubescent, trichomes appressed, branched.

Fruits

usually divaricate-ascending, rarely horizontal, not appressed to rachis, not secund, usually curved, edges parallel, (6–)8–13 cm × 1.5–2.2 mm;

valves glabrous or trichomes relatively few, scattered;

ovules 90–250 per ovary;

style 0.01–0.5 mm.

usually divaricate-descending or horizontal, rarely widely pendent, not appressed to rachis, not secund, straight or slightly curved, edges parallel, 3–4.5 cm × 2.5–3 mm;

valves sparsely pubescent to glabrate;

ovules 20–24 per ovary;

style 1.5–2 mm.

Seeds

uniseriate or sub-biseriate, 1.5–1.7 × 1–1.2 mm;

wing continuous, 0.1–0.2 mm wide.

uniseriate, 2–2.5 × 1.5–1.8 mm;

wing continuous, to 0.2 mm wide.

Boechera arcuata

Boechera serpenticola

Phenology Flowering Mar–Jun. Flowering Mar–Jun.
Habitat Rocky hillsides and cliffs in pine forests and chaparral Serpentine ridges and talus
Elevation 300-1800 m (1000-5900 ft) ca. 1100 m (ca. 3600 ft)
Distribution
from FNA
CA
[WildflowerSearch map]
[BONAP county map]
from FNA
CA
Discussion

Although usually treated as a variety of Arabis (Boechera) sparsiflora (e.g., R. C. Rollins 1993), B. arcuata is easily distinguished from that species by having rachises and fruiting pedicels pubescent with subappressed, 2–4-rayed trichomes and a geographic range limited to southern and western California. By contrast, B. sparsiflora has rachises and fruiting pedicels with spreading, usually simple trichomes (sometimes glabrescent) and an allopatric distribution north and east of the Sierra Nevada.

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

Boechera serpenticola has been confused with B. subpinnatifida but is easily distinguished by its entire (versus subpinnatifid to dentate) leaves, shorter (6–8 versus 9–14 mm) petals, and longer (1.5–2 versus 0.5–1 mm) styles. It is known only from Shasta and Trinity counties in north-central California.

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

Source FNA vol. 7, p. 365. FNA vol. 7, p. 406.
Parent taxa Brassicaceae > tribe Boechereae > Boechera Brassicaceae > tribe Boechereae > Boechera
Sibling taxa
B. acutina, 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. 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. saximontana, B. schistacea, B. serotina, 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 Streptanthus arcuatus, Arabis holboellii var. arcuata, Arabis maxima, Arabis sparsiflora var. arcuata
Name authority (Nuttall) Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 64. (2006) Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 82. (2006)
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