OregonFlora: Boechera arcuata vs. Boechera retrofracta

	Boechera arcuata	Boechera retrofracta
		reflexed rockcress, secund rockcress
Habit		Plants biennial or short-lived perennial; with or without caudices.
Stems		1.5–7(10.5) dm; lower parts densely pubescent with short-stalked, 2–8-rayed trichomes; upper parts sparsely pubescent.
Basal leaves		oblanceolate, 2–7 mm wide; margins entire or shallowly dentate; surfaces densely pubescent with short-stalked, 5–10-rayed trichomes, occasionally ciliate at petiole bases.
Cauline leaves		15–40, concealing stem proximally, bases auriculate or very rarely not; uppermost pubescent.
Inflorescences		15–80(140)-flowered, fruiting pedicels recurved at bases.
Flowers		sexual, pendent at anthesis; sepals pubescent; petals 4–8 × 0.8–2.2 mm, white to lavender; pollen ellipsoid; ovules (60)70–116 per ovary.
Fruits		strongly reflexed, usually appressed to rachis, occasionally somewhat secund; straight, 3.5–9 cm × 0.9–1.8 mm; margins parallel, glabrous or pubescent.
Seeds		uniseriate, 1–1.4 × 0.9–1.2 mm; wings continuous; to 0.1 mm wide.
2n		=14.

	Boechera arcuata	Boechera retrofracta
Distribution	[WildflowerSearch map] [BONAP county map]	[WildflowerSearch map] [BONAP county map]
Discussion		Open hillsides, sagebrush, sandy slopes, rock outcrops, oak woodlands, gravel bars, sandy banks in grasslands, open conifer forests. Flowering Apr–Aug. 700–2800 m. BR, BW, Casc, ECas, Lava, Owy, Sisk. CA, ID, NV, WA; north to AK, northeast to Quebec, east to WY, southeast to UT. Native.
Source		Flora of Oregon, volume 2, page 456 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. subpinnatifida, 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. lyallii, B. microphylla, B. paddoensis, B. pauciflora, B. paupercula, B. pendulocarpa, B. pinetorum, B. platysperma, B. pratincola, B. puberula, B. rectissima, B. rollei, B. sparsiflora, B. stricta, B. subpinnatifida, B. suffrutescens
Synonyms		Arabis holboellii, Arabis holboellii var. retrofracta, Arabis secunda, Boechera holboellii, Boechera holboellii var. secunda
Web links	Local floras: CA Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search	Local floras: BC, CA, OR, WA Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Boechera arcuata

Boechera retrofracta

reflexed rockcress, secund rockcress

Habit

Plants biennial or short-lived perennial; with or without caudices.

Stems

1.5–7(10.5) dm; lower parts densely pubescent with short-stalked, 2–8-rayed trichomes; upper parts sparsely pubescent.

Basal leaves

oblanceolate, 2–7 mm wide;

margins entire or shallowly dentate;

surfaces densely pubescent with short-stalked, 5–10-rayed trichomes, occasionally ciliate at petiole bases.

Cauline leaves

15–40, concealing stem proximally, bases auriculate or very rarely not; uppermost pubescent.

Inflorescences

15–80(140)-flowered, fruiting pedicels recurved at bases.

Flowers

sexual, pendent at anthesis;

sepals pubescent;

petals 4–8 × 0.8–2.2 mm, white to lavender;

pollen ellipsoid;

ovules (60)70–116 per ovary.

Fruits

strongly reflexed, usually appressed to rachis, occasionally somewhat secund; straight, 3.5–9 cm × 0.9–1.8 mm;

margins parallel, glabrous or pubescent.

Seeds

uniseriate, 1–1.4 × 0.9–1.2 mm;

wings continuous; to 0.1 mm wide.

=14.

Boechera arcuata

Boechera retrofracta

Distribution

[WildflowerSearch map]

[BONAP county map]

[WildflowerSearch map]

[BONAP county map]

Discussion

Open hillsides, sagebrush, sandy slopes, rock outcrops, oak woodlands, gravel bars, sandy banks in grasslands, open conifer forests. Flowering Apr–Aug. 700–2800 m. BR, BW, Casc, ECas, Lava, Owy, Sisk. CA, ID, NV, WA; north to AK, northeast to Quebec, east to WY, southeast to UT. Native.

Source

Flora of Oregon, volume 2, page 456
Ihsan Al-Shehbaz

Sibling taxa