Al Schneider's Rocky Mountains Plant Descriptions

Two-grooved Milkvetch
Astragalus bisulcatus
Pea family (Fabaceae)

For Astragalus bisulcatus variety haydenianus


©2005 Matt Lavin
Two-grooved Milkvetch is a large showy plant growing to several feet tall and wide and producing hundreds of flowers. It is also a real stinker as it almost always grows on Selenium soils and exudes a strong odor. The was named by Linnaeus in 1753; the word "Astragalus" means "ankle bone" in Greek and is an ancient Greek plant name perhaps given because of the seed shape in some members of the Astragalus or because the Greeks used rattling bones for dice and the sound made is similar to the rattling of dry Astragalus seeds in the pod. William Jackson Hooker named this plant in 1831 from a specimen collected by Thomas Drummond on the "Plains of the Saskatchewan" around 1826. "Bisulcatus" is Latin for "two-grooved" and refers to the deep grooves on both sides of the seed pod.

This species has, according to John Kartesz, two varieties: bisulcatus and haydenianus. However, Colorado flora expert Bill Weber considers these to be two distinct species.

Description

, with stems to 2 1/2' tall, spreading from roots. Leaves to 6+" long. 15-35, 1/5-1+" long, less than 1/2" wide. 1-5" long. 25-80 flowered, flowers at first erect in bud and then drooping, pedicles very short. Flowers 1/3 to 3/4" long light yellow, white, white tinged pink, tinged purple depending on location and variety. Pods with about as long as tube, , hairy or , and with two grooves ("bisulcate").

Field Marks

Shrub-like milkvetch with numerous candle-like flower clusters and seeds with 2 deep grooves.

© Al Schneider

genus -- A subdivision of a botanical Family in which all members have a significant number of similar characteristics.

A peduncle is a common stalk of a cluster of flowers.

A perennial plant lives and blooms for many years.

A stipe is a small stalk that supports some other structure. In ferns, the stalk of a frond; generally a small stalk.

calyx -- the sepals of a flower, typically forming a whorl that encloses the petals and forms a protective layer around a flower in bud.

compressed -- flattened lengthwise, either laterally (from side to side) or dorsally (from front to back).

hanging or drooping.

A raceme is an unbranched, indeterminate type of inflorescence bearing flowers having short floral stalks along its axis.

glabrous -- smooth, glossy, having no bristles or hair-like structures. Bald.

leaflets -- Each little leaf-like thing in a compound leaf is a leaflet.