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

Balloon Milk-vetch, Balloonpod Milkvetch, Balloon-pod Milk-vetch, Whitney's Balloon Milkvetch

Astragalus whitneyi var. sonneanus

Synonym: Astragalus whitneyi ssp. hookerianus

Balloon milk-vetch from Squaw Creek Overlook, off I-84 east of Pendleton, OR......late May, 1999.

The photo at right shows a close-up of the creamy, yellowish, or somewhat purple-tinged flowers of balloon milk-vetch.

Characteristics:

Also known as balloon pod milk-vetch, balloon milk-vetch is a perennial with with several to many branched stems that are spreading and clustered close to the ground. Plants range from 10-20 cm high and the foliage ranges from green to covered with silvery hairs. The compound-pinnate leaves are tufted close to the ground, measure 2.5-4 cm long, and bear 9-21 leaflets. Individual leaflets are narrowly oblong to obovate in shape 6-10 mm long. The upper surface of the leaflets ranges from glabrous to sparsely haired while the lower surface is covered with appressed hairs.

The flower stems are longer than the upper leaves and topped by a short, dense raceme of 5-20 flowers up to 1.5 cm long, and not elongating much in fruit. The tubular, bell-shaped calyx 4-5 mm long with triangular, awl-shaped teeth up to 2 mm long. The corolla is pinkish, lavender-purple, or yellowish and measures up to 1 cm long. The pod is greatly inflated, somewhat pear-shaped, clear with reddish or purple blotches over the surface. The pods measure 2.5-3 cm long and are very thin-walled and sparsely covered with minute, appressed hairs (See photos.).

Habitat:

Balloon milk-vetch is found on rocky outcrops and mountain crests at higher elevations, frequently on serpentine rock (especially in the Siskiyous). It is typically found between the elevations of 1300-3600 meters.

Range:

Balloon milk-vetch is widely distributed east of the Cascade Mts, from central Washington south to northeastern California, east to Nevada and southwest Idaho.

The distinctive pods of balloon milkvetch as seen along the Ironstone Trail #1141, William O. Douglas Wilderness........July 25, 2015.

The photo above shows a close-up of the red-mottled pods of balloon milk-vetch from the Blue Mts of Oregon.........late May, 1999. Note the numerous, appressed hairs on the surface of the pods.

The photo above shows the form of the leaves on the stem and the racemes which are about equal to or slightly above the upper leaves. Photographed from Squaw Creek Overlook, off I-84 east of Pendleton, OR...........late May, 1999.

Pod of Balloon Milk-vetch, Balloonpod Milkvetch, Balloon-pod Milk-vetch, Whitney's Balloon Milkvetch: Astragalus whitneyi var. sonneanus (Synonym: Astragalus whitneyi ssp. hookerianus)

The photo above shows a pod, slightly arched where the body joins the stipe. Photographed from Squaw Creek Overlook, off I-84 east of Pendleton, OR...........late May, 1999.

The photo above shows a close-up side view of the corolla and calyx of balloon milk-vetch as seen where Oregon Highway 78 crosses the pass across the north end of the Steens Mt. at the Harney and Malheur County line..........May 29, 2000.

Pods of Balloon Milk-vetch, Balloonpod Milkvetch, Balloon-pod Milk-vetch, Whitney's Balloon Milkvetch: Astragalus whitneyi var. sonneanus (Synonym: Astragalus whitneyi ssp. hookerianus)

The photo above shows the red-mottled pods of balloon milk-vetch as commonly held against the ground. Photographed where Oregon Highway 78 crosses the pass across the north end of the Steens Mt. at the Harney and Malheur County line..........May 29, 2000.

Paul Slichter