[Milk-vetches: The Genus Astragalus East of the Cascade Mts. of Oregon and Washington]

Curvepod Milk-vetch, Threadstalk Milk-vetch, Medic Milk-vetch, Spiral-pod Milk-vetch

Astragalus speirocarpus

Close-up views of curvepod milk-vetch as seen along Alderdale Road about 3 miles north of its junction with Washington Highway SR14 in eastern Klickitat County..........April18 and 25, 2010.

Leaves of curvepod milk-vetch along the old Vantage-Ellensburg, WA highway........May 3, 1998.

Characteristics:

Curvepod milk-vetch is a tufted, numerous branched, prostrate perennial with spreading to ascending stems from 10-40 cm long. Its herbage is gray, with numerous short microscopic hairs that are sharp, stiff and appressed to the stems and leaves. The pinnately compound leaves are 3 to 6 cm in length, with 9 to 17 leaflets which are oblong and rounded to obovate with blunt or notched tips.

The flower stems are shorter than or about equal to the upper leaves. The spreading or ascending flowers are found in loose to closely flowered racemes of ten to forty flowers. The flowers are white to lavender in color, often with a bluish tinge (especially the keel). Individual flowers are 14 to 20 mm in length. The wings are two to four mm longer than the keel.

The tubular calyx is grayish, hairy, and 6 to 9 mm in length. The calyx teeth have short, triangular teeth less than one-fourth the length of the tube.

The distinctive seed pods are pendulous, with strongly compressed bodies, and usually coiled 1.5 to 2.5 turns. The surface of the pods is marked with reddish specks and bears a fair amount of appressed, stiff hairs.

Habitat:

Curvepod milk-vetch is found on rocky sagebrush slopes near the Columbia River.

Range:

Curvepod milk-vetch is found in central Washington in Yakima, Kittitas, Klickitat, and Benton counties.

Inflorescence of curvepod milk-vetch along the old Vantage-Ellensburg, WA highway........May 3, 1998.

This photo shows the ripening seed pods of curvepod milk-vetch as seen in the roadcut along Washington Highway 14 just east of Roosevelt, WA..........June 2, 2008.

This photo shows a close-up of the pinnately compound leaf of curvepod milk-vetch as seen in the roadcut along Washington Highway 14 just east of Roosevelt, WA.........June 2, 2008.

This photo shows a close-up of the distinct, coiled seed pod of curvepod milk-vetch as seen in the road cut along Washington Highway 14 just east of Roosevelt, WA........June 2, 2008.

Seed pods of curvepod milk-vetch along the old Vantage-Ellensburg, WA highway........May 3, 1998.

Curvepod Milk-vetch, Threadstalk Milk-vetch, Medic Milk-vetch, spiral-pod Milk-vetch: Astragalus speirocarpus

Prostrate growth pattern of curvepod milk-vetch........May 3, 1998.

Paul Slichter