[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 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.
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.
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.
The photo above shows the narrow leaflets and racemes with pods
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