[Rockcresses: The Genus Arabis (and Boechera) East of the Cascade Mountains of Oregon and Washington]

Elegant Rockcress, Purple Sicklepod Rockcress, Sicklepod Rockcress, Sickle-pod Rock Cress

Boechera atrorubens

Synonyms:Arabis atrorubens, Arabis sparsiflora, Arabis sparsiflora var. atrorubens

Elegant Rockcress, Purple Sicklepod Rockcress, Sicklepod Rockcress, Sickle-pod Rock Cress: Boechera atrorubens (Synonyms: Arabis atrorubens, Arabis sparsiflora, Arabis sparsiflora var. atrorubens) - Elegant Rockcress, Purple Sicklepod Rockcress, Sicklepod Rockcress, Sickle-pod Rock Cress: Boechera atrorubens (Synonyms: Arabis atrorubens, Arabis sparsiflora, Arabis sparsiflora var. atrorubens) - Elegant Rockcress, Purple Sicklepod Rockcress, Sicklepod Rockcress, Sickle-pod Rock Cress: Boechera atrorubens (Synonyms: Arabis atrorubens, Arabis sparsiflora, Arabis sparsiflora var. atrorubens)

The striking flowers of purple sickle-pod rockcress as seen on scablands at the Bickleton Ridge Unit of the Klickitat Wildlife Area..........April 20, 2018. Note the numerous branched hairs at the tips of each purplish sepal.

Characteristics:

Sicklepod rockcress is a biennial or short-lived perennial with one to several upright, simple to branched stems arising 40-80 cm from a mass of basal leaves. Plants are densely hairy below with simple to branched, star-shaped hairs. The numerous basal leaves are oblanceolate in shape, 2 to 9 cm in length and 2 to 8 mm wide. The margins are entire to several-toothed and the blades are finely to coarsely haired. The basal leaves narrow to a slender petiole. There are also numerous stem leaves, reduced in size up the stem. The lower leaves are petiolate, but the upper ones become somewhat clasping or auriculate and somewhat glabrous in texture. The stem leaves are linear-lanceolate to oblanceolate in shape, with mostly entire margins.

The infloresence is a long, loose raceme of many flowers. The 4 petals may be white to deep purple and measure 6-14 mm in length. The pedicels are glabrous to sparsely covered with branched, radiate hairs. The sepals are often purplish, covered with branched, radiate hairs, and measure 4-6 mm long. The seed capsules are siliques, long and thin, somewhat flattened, usually arched in outline, and either ascending to spreading-drooping. The capsules are glabrous and measure from 6-10 cm long and 1.75-2.5 mm wide.
Pacific Northwest Varieties:

var. atrorubens: Petals a deep purple color. Siliques ascend. Basal leaves toothed. Pedicels of the flowers and siliques typically not haired. Found east of the Washington Cascades from Chelan County to Klickitat County in the south.

var. sparsiflora: Petals white, pink, or light purplish, but lighter than variety atrorubens. Basal leaves entire margined. Pedicels of the flowers and siliques usually ascending, smooth, and hairless. Found in the eastern part of the species' range from Idaho to Utah, west to southeast Oregon, and south to northeastern California.

var. subvillosa: Petals white, pink, or light purplish, but lighter than variety atrorubens. Siliques usually spreading to descending. Basal leaves toothed. Pedicels of the flowers and siliques usually noticebly lightly haired and spreading. Found from central Washington south to California along the east base of the Cascade Range, and east to Montana and Wyoming.


Habitat:

Sicklepod rockcress is found in arid, sagebrush and ponderosa pine habitats.


Range:

Sicklepod rockcress is found from British Columbia south along the eastern edge of the Cascade Range to California, and eastward to Alberta, and south through Montana, Wyoming and into Utah.


Close-up of a flower of Elegant Rockcress, Purple Sicklepod Rockcress, Sicklepod Rockcress, Sickle-pod Rock Cress: Boechera atrorubens (Synonyms: Arabis atrorubens, Arabis sparsiflora, Arabis sparsiflora var. atrorubens) - Close-up sideviews of the flowers of Elegant Rockcress, Purple Sicklepod Rockcress, Sicklepod Rockcress, Sickle-pod Rock Cress: Boechera atrorubens (Synonyms: Arabis atrorubens, Arabis sparsiflora, Arabis sparsiflora var. atrorubens)

Close-ups of the flowers of purple sicklepod rockcress as seen along the Valley Trail to the north of the Painted Rocks trailhead, Little Spokane River Natural Area............May 6, 2012.

Elegant Rockcress, Purple Sicklepod Rockcress, Sicklepod Rockcress, Sickle-pod Rock Cress: Boechera atrorubens (Synonyms: Arabis atrorubens, Arabis sparsiflora, Arabis sparsiflora var. atrorubens) - Upward spreading fruits of Elegant Rockcress, Purple Sicklepod Rockcress, Sicklepod Rockcress, Sickle-pod Rock Cress: Boechera atrorubens (Synonyms: Arabis atrorubens, Arabis sparsiflora, Arabis sparsiflora var. atrorubens)

Purple sicklepod rockcress blooming atop Bickleton Ridge in the Bickleton Ridge Unit of the Klickitat Wildlife Area.......May 7, 2017.

Inflorescence of Elegant Rockcress, Purple Sicklepod Rockcress, Sicklepod Rockcress, Sickle-pod Rock Cress: Boechera atrorubens (Synonyms: Arabis atrorubens, Arabis sparsiflora, Arabis sparsiflora var. atrorubens) - Lower stem and basal leaves of Elegant Rockcress, Purple Sicklepod Rockcress, Sicklepod Rockcress, Sickle-pod Rock Cress: Boechera atrorubens (Synonyms: Arabis atrorubens, Arabis sparsiflora, Arabis sparsiflora var. atrorubens)

Purple sicklepod rockcress as seen on Sourdough Ridge, Asotin Wildlife Area, Asotin County, WA.........June 3, 2017.

Elegant Rockcress, Purple Sicklepod Rockcress, Sicklepod Rockcress, Sickle-pod Rock Cress: Boechera atrorubens (Synonyms: Arabis atrorubens, Arabis sparsiflora, Arabis sparsiflora var. atrorubens)

The striking flowers of sickle-pod rock cress from the crest of the Columbia Hills, Columbia River Gorge...........early April, 2005. Note the numerous branched hairs at the tips of each purplish sepal.

Elegant Rockcress, Purple Sicklepod Rockcress, Sicklepod Rockcress, Sickle-pod Rock Cress: Boechera atrorubens (Synonyms: Arabis atrorubens, Arabis sparsiflora, Arabis sparsiflora var. atrorubens)

Siliques of Elegant Rockcress, Purple Sicklepod Rockcress, Sicklepod Rockcress, Sickle-pod Rock Cress: Boechera atrorubens (Synonyms: Arabis atrorubens, Arabis sparsiflora, Arabis sparsiflora var. atrorubens)
The photo above shows the erect fruits of sickle-pod rock cress.

Paul Slichter