[The Milk-vetch East of the Cascade Mts.]

Woolly-pod Milk-vetch

Astragalus purshii

The photo above shows a close-up of woolly-pod milk-vetch as seen in sagebrush lands in the Gingko State Park to the west of Vantage, WA...............March 29, 2007.

The photo at right shows a close-up of the flowers of woolly-pod milk-vetch as seen along The Dalles Mountain Road northeast of The Dallesport, WA.
Characteristics:

Also known as Pursh's milk-vetch, woolly-pod milk-vetch is an attractive perennial wildflower both in flower and in fruit. It is a loosely to densely matted plant with very short stems, or often lacking stems all together. The foliage is densely covered with many whitish, woolly to cottony hairs. When present, the prostrate stems range from 0-10 cm long. The pinnately compound leaves are 1-12 cm long and bear from 5-17 leaflets. Individual leaflets are rounded to obovate or even narrowly elliptic or oblanceolate and measure from 2-14 mm long.

The flower stems are incurved and ascending in bloom, later becoming prostrate in fruit (See photo above.). They measure from 0.5-10 cm long and are tipped with 2-12 ascending flowers in a short raceme. The calyx is a long bell or tubular in shape and measures 6-17 mm long. The calyx teeth range from lance to awl shaped, or may be broadly triangular and range from 1-6 mm long. The outer surface of the calyx is covered with white to grayish-brown hairs. The corolla measures 20-25 mm long and varies from white to yellowish, pale pink or "hot" pink-purple. The banner measures 9-25 mm long and is gently recurved from the axis of the tube and bears a whitish central spot with pink to purple venation. The wings are 1-3 mm shorter than the banner while the keel is 8-21 mm long. The distinctive fruits are densely covered by long, whitish, woolly hairs from 1.5-5 mm long. They are ovoid to lance-ellipsoid in shape, slightly curved in profile and depressed above, and measure 7-27 mm long and 3.5-11 mm wide.


Varieties of Woolly-pod Milk-vetch Found East of the Cascade Mts. of Oregon and Washington:

Gravel Milkvetch, Woollypod Milkvetch: Astragalus purshii var. glareosus (Synonyms: Astragalus glareosus, Astragalus ventosus) - Petals pink or pink-purple. Flowers 20-25 mm long, the banner 15-26 mm long. Calyx 9-17 mm long. Pods moderately incurved or arched, measuring 15-30 mm long. Found across eastern Washington, and in the northern half of Oregon south to the southern edge of the Blue Mts and east to the north of the Steens Mt. across the Snake River Plains to northwestern Utah.

Hare Milkvetch, Woollypod Milkvetch: Astragalus purshii var. lagopinus (Synonym: Astragalus lagopinus) - Racemes 1-5 flowered. Petals pink or pink-purple. Flowers smaller, 10-16 mm long with calyx 5.5-9 mm long. Pods 7-15 mm long, slightly to strongly incurved, often through a half circle or further. In Oregon, found from Deschutes County south to the California border and east to southeastern Oregon.

Snake River Milkvetch ? : Astragalus purshii var. ophiogenes (Synonym: Astragalus ophiogenes) - Racemes 5-11 flowered. Petals pink or pink-purple. Flowers smaller, 10-16 mm long with calyx 5.5-9 mm long. Pods 8-13 mm long, strongly incurved, often nearly forming a complete spiral. Found from the Owhyee Canyon of southeastern Oregon into southwestern Idaho.

Pursh's Milkvetch, Woollypod Milkvetch: Astragalus purshii var. purshii (Synonyms: Astragalus incurvus, Astragalus purshii var. interior) - Very similar to var. tinctus. Petals, except for tip of keel, whitish or creamy whitish-yellow. Flowers 20-30 mm long, the banner 15-26 mm long. Calyx 9-17 mm long. Pods 13-27 mm long, not ventrally depressed or only slightly incurved (scarecely arched). Found scattered across much of eastern Oregon and Washington although evidently absent from the central portion of Oregon.

Woollypod Milkvetch: Astragalus purshii variety tinctus (Synonyms: Astragalus candelarius, Astragalus lectulus, Astragalus leucolobus, Astragalus leucolobus ssp. consectus, Astragalus purshii var. lectulus, Astragalus purshii var. longilobus) - Very similar to var. purshii. Petals pale pink to vivid pink-purple. Flowers 20-25 mm long, the banner 15-26 mm long. Calyx 9-17 mm long. Pods 13-27 mm long, not ventrally depressed or only slightly incurved (scarecely arched). Found across south-central to southeastern Oregon.


The photo above shows woolly-pod milk-vetch (variety purshii) as seen in the Horse Heaven Hills near Benton City, WA..............April 18, 2002.

Similar Species:

Hairy Milk-vetch: Astragalus inflexus - Foliage densely whitish pubescent. Ascending stems from 10-40 cm long. Purplish corolla 18-22 mm long. Found from both shores of the Columbia River to the east of Rock Creek and north into central Washington and east to western Montana.

Newberry's Milk-vetch: Astragalus newberryi - Foliage densely silvery pubescent or with satiny, appressed hairs. Leaflets broadly obovate. Whitish, yellowish, or commonly pink or purplish corolla 2-2.5 cm long. In our area, found from Crook County in central Oregon south to southeastern Oregon, Nevada and California.

Pursh's Milk-vetch: Astragalus purshii - Foliage densely whitish pubescent. Depressed stems from 0-10 cm long. Purplish corolla 2.5-3 cm long. Found across much of central and eastern Washington and Oregon.


The photo above shows the leaf of woolly-pod milk-vetch as photographed above Doug's Beach, above Washington Highway 14 to the east of Lyle, WA (Columbia River Gorge).............March 1998.

Habitat:

Woolly-pod milk-vetch may be found on prairies and in the sagebrush desert from the foothills to moderate elevations in the mountains.


Range:

Woolly-pod milk-vetch is distributed east of the Cascade Mountain range from southern British Columbia south to northern California, and eastward in Canada to Alberta, and south through the Dakotas into Utah, Nevada, and New Mexico.


The photo above shows a close-up of the flowers and leaves of woolly-pod milk-vetch as seen in sagebrush lands in the Gingko State Park to the west of Vantage, WA...............March 29, 2007.

The photo above shows a close-up of the woolly pod of woolly-pod milk-vetch (variety lagopinus?) as seen several miles south of Mitchell, OR............June 23, 1998.

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The photos above show views of the same woolly-pod milk-vetch as seen along the access road to Selah Butte, northeast of Selah, WA.......................March 22, 2008. The flowers should be more purplish than represented here. Click each photo to see an enlarged version.

The photo above shows woolly-pod milk-vetch (possibly variety tinctus) as seen along Long Hollow Road about 1.5 miles west of its summit (south Steens Mt., southeastern Oregon)..................May 27, 2000.

Woolly-pod milk-vetch along The Dalles Mountain Road northeast of The Dallesport, WA.........4/13/91.

Paul Slichter