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Photo at right of leaf
of Yakima milk-vetch atop the Horse Heaven Hills west of Richland, WA......April
17, 1998.
Yakima milk-vetch is an attractive perennial wildflowers with several to many clustered stems from 2-20 cm high. The stems and leaves are greenish to grayish in color, and when bearing hairs, sparsely haired with minute, straight, stiff, sharp and appressed hairs. The 17-37 leaflets on the pinnately compound leaves are narrowly linear and measure up to 25 mm long and up to 2-3 mm wide.
The fairly stout flower stems hold the terminal racemes equal to or higher than the highest leaves. The flower racemes are tightly to loosely clustered, with 7-35 flowers. The flowers are yellow-white to purple-tinged. The banner is held upwards at an angle up to about 45 degrees and is longer than the wings. The thin wings are in turn longer than the keel. The bell-shaped calyx is covered with grayish to black hairs and measures 8-12 mm long, with thin, awl-shaped teeth 2.5-5 mm long. The glabrous pod is held erect and measures from 1.5-3 cm long.
Idaho Milk-vetch: Astragalus conjunctus - Caylx cylindrical, 6-15 mm long, about 2 times as long as thick. Calyx teeth 1.5-3 mm long. Corolla white or with purplish tip to keel and banner. Leaflets 13-31. Pod glabrous. Found from Wasco County, northcentral Oregon east to the Blue mts. and south to the the Steens Mt. and east to southwestern Idaho.
Hood River Milk-vetch: Astragalus hoodianus - Calyx bell-shaped, 11-15 mm long, about 1.5 times as long as thick. Calyx teeth 4.5-7.5 mm long. Leaflets 17-37. Pod pubescent. Found near the Columbia River Gorge in Wasco and Hood River Counties in Oregon and Klickitat County in Washington.
Yakima Milk-vetch: Astragalus reventiformis - Calyx bell-shaped, 8-12 mm long, about 1.5 times as long as thick. Calyx teeth 2.5-5 mm long. Leaflets 17-37. Pod pubescent. Found from Kittitas County in Washington near Ellensburg south to Klickitat County, Washington and south into Sherman County of Oregon.
Blue Mt. Milk-vetch: Astragalus reventus - Leaflets 23-41. Pod glabrous. Found in the Blue Mts. of northeastern Oregon near the headwaters of the Umatilla and Grande Ronde Rivers into southeastern Washington.
Sheldon's Milk-vetch: Astragalus sheldonii - Leaflets 23-41. Pod usually pubescent. Found from southern Asotin County in southeastern Washington south into Wallowa County, northeastern Oregon and into Lewis and Nez Perce Counties in Idaho.
Yakima milk-vetch may be found growing in the sagebrush desert, scablands, grasslands, ponderosa forests, and stony flats from the foothills into the lower mountains.
Yakima milk-vetch is distributed in the Yakima River drainage, from Ellensburg, WA south to the Horse Heaven Hills and Columbia Hills along the Columbia River. Evidently it is found at one spot on the Oregon side of the river in Sherman County.
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