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Boechera subpinnatifida

ashy rockcress

Lyall's slender rockcress

Habit Plants long-lived perennial; with woody caudices. Plants long-lived perennial, cespitose; with woody caudices.
Stems

1–4(5) dm; lower parts with short-stalked, 2–6-rayed trichomes; upper parts sparsely pubescent.

0.3–1.5(2) dm, glabrous.

Basal leaves

narrowly oblanceolate, 1–4(5) mm wide;

margins prominently dentate to subpinnatifid; entire on those of sterile shoots;

surfaces densely pubescent with short-stalked; (2)4–9-rayed trichomes, ciliate near petiole bases with simple or 2-rayed trichomes.

linear-oblanceolate, 1–5(8) mm wide;

margins entire, usually ciliate at least proximally with simple and/or short-stalked, 2- or 3-rayed trichomes, or rarely youngest leaves of sterile shoots pubescent with 4–6-rayed trichomes;

margins with stalked trichomes.

Cauline leaves

(10)20–60, often concealing stem throughout, bases uppermost auriculate and sparsely to moderately pubescent.

1–5, mostly not concealing stem, bases auriculate or rarely not, glabrous.

Inflorescences

8–30-flowered, fruiting pedicels reflexed, strongly recurved, 5–15 mm, with appressed, branched trichomes.

2–10(15)-flowered, fruiting pedicels erect; straight, 3–8(15) mm, glabrous.

Flowers

sexual, divaricate-ascending to pendent at anthesis;

sepals glabrous;

petals 9–14 × 1.5–3 mm, purple or rarely lavender;

pollen ellipsoid;

ovules 24–42 per ovary;

styles 0.5–1 mm.

sexual or apomictic; erect at anthesis;

sepals glabrous;

petals 6–8.5 × 1.5–3 mm, white to lavender; sexual pollen ellipsoid, apomictic pollen spheroid;

ovules 34–64 per ovary;

styles 0.1–0.7 mm.

Fruits

pendent, not appressed to rachis, not secund; straight to slightly curved; (3.5)5–8 cm × 2–3 mm;

margins parallel, pubescent.

erect, appressed to rachis, not secund; straight, 3–5.6 cm × 1.5–2.5 mm;

margins parallel, glabrous.

Seeds

uniseriate, 2.5–3.5 × 1.5–2.2 mm;

wings continuous or at both ends, 0.4–0.8 mm wide.

subbiseriate, 1.5–2 × 1–1.5 mm;

wings continuous, 0.3–0.5 mm wide.

2n

=14.

Boechera subpinnatifida

Boechera lyallii

Distribution
[WildflowerSearch map]
[BONAP county map]
[WildflowerSearch map]
[BONAP county map]
Discussion

Talus, rock outcrops, gravelly soil, sagebrush-grassland communities. Flowering Mar–Jun. 100–1800 m. Lava, Sisk. CA, ID, NV; southeast to UT. Native.

Talus slopes, cliffs, gravelly soil in alpine and subalpine habitats. Flowering Jun–Aug. 1700–3000 m. BR, BW, Casc. CA, ID, NV, WA; north to Yukon, northeast to MT, southeast to UT. Native.

Source Flora of Oregon, volume 2, page 457
Ihsan Al-Shehbaz
Flora of Oregon, volume 2, page 453
Ihsan Al-Shehbaz
Sibling taxa
B. acutina, B. atrorubens, B. breweri, B. calderi, B. cascadensis, B. cobrensis, B. covillei, B. cusickii, B. davidsonii, B. divaricarpa, B. drepanoloba, B. hastatula, B. horizontalis, B. howellii, B. koehleri, B. lemmonii, B. lyallii, B. microphylla, B. paddoensis, B. pauciflora, B. paupercula, B. pendulocarpa, B. pinetorum, B. platysperma, B. pratincola, B. puberula, B. rectissima, B. retrofracta, B. rollei, B. sparsiflora, B. stricta, B. suffrutescens
B. acutina, B. atrorubens, B. breweri, B. calderi, B. cascadensis, B. cobrensis, B. covillei, B. cusickii, B. davidsonii, B. divaricarpa, B. drepanoloba, B. hastatula, B. horizontalis, B. howellii, B. koehleri, B. lemmonii, B. microphylla, B. paddoensis, B. pauciflora, B. paupercula, B. pendulocarpa, B. pinetorum, B. platysperma, B. pratincola, B. puberula, B. rectissima, B. retrofracta, B. rollei, B. sparsiflora, B. stricta, B. subpinnatifida, B. suffrutescens
Synonyms Arabis subpinnatifida Arabis lyallii, Arabis lyallii var. lyallii
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