Arcane Milkvetch, Arcane Milk-vetch: Astragalus obscurus (Synonym: Synonym: Astragalus miser)

The photo above shows a close-up of the front of the veined banner and the central wings surrounding the keel of arcane milk-vetch. Photographed along Oregon Highway 78 at the county line between Hareney and Malheur Counties..........May 29, 2000.

Arcane milk-vetch is a perennial wildflower with a cluster of spreading to erect stems from 5-15 cm tall. The leaves and stems are greenish and minutely haired with the hairs stiff and appressed to the stem or blade. The pinnately compound leaves are 3.5-10 cm long with 7-13 leaflets that are linear to oblong-elliptic in outline and 2-12 mm long. The leaf petioles are slender but stiff.

The inflorescence is a 5-15 flowered raceme from 1-6 cm long. The bell-shaped calyx is 3.5-5.5 mm long with black and white hairs appressed to the tube. The narrow to broad calyx teeth are awl-shaped and measure 0.4-1.6 mm long. The corolla is whitish-yellow, dirty white or whitish tinged with lilac. The banner is 7-10.5 mm long while the wings are up to 9.5 mm long while the keel is slightly longer than the wings. The nearly sessile pod is held erect. It is linear-oblong in outline and straight, and measures 12-25 mm long and 2.5-3.5 mm wide.

Arcane milk-vetch may be found on rocky flats, hillsides and ridge amongst low sagebrush between the elevations of 1100-2400 meters.

Arcane milk-vetch may be found from the Burnt, John Day and Deschutes Rivers of central Oregon and southward to the foothills to the east of the Cascade Mts. of California. It is found eastward through southeastern Oregon to southern Idaho and northern Nevada.

Arcane milk-vetch blooming on rocky flats near the summit ridge of Hart Mt. to the west of Hot Springs Campground, Hart Mt. National Antelope Refuge........June 9, 2016.

Additional images of arcane milkvetch as seen on gravelly slopes at Domingo Pass in the Pueblo Mountains of southeastern Oregon.........May 31, 2012.

The photo above shows a close-up of the leaf of arcane milk-vetch photographed about 2 miles south of Frenchglen, OR..........May 27, 2000.

Arcane milk-vetch as seen in mid Fall on north-facing slopes of Sulphur Ridge in the South Fork Crooked River Wilderness Study Area...........October 25, 2015.

The photo above shows a close-up of the pods of arcane milk-vetch photographed about 2 miles south of Frenchglen, OR..........May 27, 2000.

Leaflets of Arcane Milk-vetch: Astragalus obscurus (Synonym: Astragalus miser)

The photo above shows the scurfy surface to the leaflets of arcane milk-vetch. Photographed near Picture Rock Pass on Oregon Highway 31..........July 12, 1998.