Photo
of the pods of sickle milkvetch (Astragalus curvicarpus var. curvicarpus)
near Domingo Pass, Pueblo Mts......6/25/99. The pods may be fully coiled like
pictured at right, or may be more fishhook in appearance. The pubescence present
on this variety of sickle milk-vetch is not evident in this photo.
Also known as coil-pod milk-vetch, sickle milk-vetch is a perennial milk-vetch with several to many unbranched to branched stems from 15-40 cm long arising from a shallow, buried crown atop a stout taproot. The stems are spreading to ascending and are covered with at least some incurved, curly or spreading hairs. The compound-pinnate leaves bear 9-17 leaflets and range from 3- 8 cm in length, with the obovate-cuneate, oblong-elliptic, or oblanceolate leaflets each measuring from 5-20 mm long (See photo below.).
The stout flower stem is shorter than or equal to the higher leaves and are topped by racemes that are loosely to tightly clustered, with 10-30 flowers. The flowers are spreading early in bloom but soon reflex downwards. The calyx is broadly cylindrical in shape and measures 6-8 mm long with black hairs on it. The calyx lobes are triangular and very short. The corolla is yellowish-white with variable banner and keel (See the variety descriptions below.). The pod is sickle-shaped or coiled, generally being smooth-surfaced or glabrous, or somewhat pubescent in variety curvicarpus. (See photo at right.). The pods measure from 1.5-2.5 cm long and are about 4 mm wide. They taper to a point at both ends.
variety brachycodon - Ovary and mature pod glabrous. Calyx 6-8.5 mm long. Banner 13.5-15.5 mm long. Keel 9.5-11.5 mm long. leaflets pubescent on the upper surfaces. Found on the upper reaches of the Deschutes River from about 20 miles NE of Madras, OR south into Jefferson, Crook and Deschutes Counties.
variety curvicarpus - Ovary and mature pod pubescent. Banner 16-20 mm long. Keel 12-15 mm long. Upper surface of leaflets pubescent (See photo below.). Found from the southwestern edge of the Blue Mts. of Oregon south to Klamath Falls, OR and east across Lake County to Malheur and Harney Counties and east into the Snake River Plains of southern Idaho and south to California and Nevada.
variety subglaber - Ovary and mature pod glabrous. Calyx 9-13.5 mm long. Banner 13.9-19.5 mm long. Keel 11.5-14.5 mm long. Leaflets nearly glabrous. Found near the lower reaches of the Deschutes and John Day Rivers of Grant and Wasco Counties south to northern Jefferson County.
Sagebrush desert, from the foothills into the lower mountains. It commonly grows on porous sandy, gravelly soils, and occasionally on sand dunes.
Sickle milk-vetch is distributed east of the Cascade Mts, from central Washington south to northern California, east to Nevada and southwest Idaho.
