[Rock Cresses: The Genera Arabis and Boechera in the Columbia River Gorge of Oregon and Washington]

Elegant Rockcress, Purple Sicklepod Rockcress, Sicklepod Rockcress

Boechera atrorubens

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

Elegant Rockcress, Purple Sicklepod Rockcress, Sicklepod Rockcress, Sickle-pod Cress: Arabis sparsiflora var. atrorubens (Synonyms: Arabis atriflora, Arabis atrorubens, Arabis sparsiflora, Boechera 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 Cress: Arabis sparsiflora var. atrorubens (Synonyms: Arabis atriflora, Arabis atrorubens, Arabis sparsiflora, Boechera atrorubens)The photo at right shows the clasping leaves of sickle-pod rock cress.

Characteristics:

Sickle-pod is a biennial or short-lived perennial with one to several stems arising from a basal tuft of leaves. The stems may be simple or often are branched. The stems arise from 30-100 cm an are often covered with many simple to branched hairs, especially near the base. The basal leaves are plentiful, from 2-9 cm long and 2-8 mm wide, with an oblanceolate shape tapering gradually to the stem. The margins are entire to coarsely toothed. The lower leaf surfaces are often densely haired. The stem leaves are petiolate to clasping and auriculate, from 2-8 cm long and 2-6 mm wide.

The inflorescence is a many-flowered raceme at the tip of each stem or branch. The 4 sepals are 3-6 mm long, and the 4 white to deep-purple petals range from 6-14 mm long. The seed capsules are long slender siliques from 4-12 cm long and 1.5-2 mm wide. The siliques are noticeably arched, and may ascend, spread, or droop depending on the variety.

Two varieties of sickle-pod mustard are found in the Pacific Northwest.

Variety atrorubens has deep purple petals, seed capsules that are ascending, and basal leaves with toothed margins. It may be found from Chelan County, WA south to the Columbia River Gorge.

Variety subvillosa has flower with white to light purple petals, seed capsules that are often arched and descending sharply, and basal leaves which may be entire to lightly toothed on the margins. It may be found from central Washington south to California, and east to Montana and Wyoming.


Habitat:

Typical habitat of sickle-pod mustard is open, sagebrush and ponderosa pine country.


Range:

Sickle-pod mustard is found from British Columbia south along the east base of the Cascade Mts. to California, and east to Alberta, Montana, Wyoming, and Utah.

In the Columbia River Gorge, variety atrorubens may be found from near Grassy Knoll in the west to Stacker Butte in the east. It is found between the elevations of 2200'-3800'.


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

Sicklepod rockcress as seen beginning to bloom at left along the crest of the Columbia Hills in the Columbia Hills Natural Area Preserve.........April 3, 2013. The photo at right shows the basal leaves and lowest stem leaves of sicklepod rockcress as seen along the crest of the Columbia Hills in the Columbia Hills Natural Area Preserve.........March 24, 2017.

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

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

Paul Slichter