Astragalus racemosus (Cream Milkvetch)
Also known as: | Racemose Milkvetch, Alkali Milkvetch, Creamy Poison-vetch, Alkali Poison-vetch |
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Genus: | Astragalus |
Family: | Fabaceae (Pea) |
Life cycle: | perennial |
Origin: | native |
Habitat: | sun; clay or chalky soil; prairies, roadsides, badlands, gullies, open woods |
Bloom season: | May - June |
Plant height: | 16 to 40 inches |
Wetland Indicator Status: | none |
MN county distribution (click map to enlarge): | |
National distribution (click map to enlarge): |
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Detailed Information
Flower:
A somewhat loose cluster of 20 to 70 pea-like flowers on a long stalk arising from the upper leaf axils, the cluster usually significantly surpassing the length of the attending leaf. Flowers are ½ to ¾ inch long, white to creamy colored or pinkish to purplish, the upper standard erect, the two laterals petals smaller and horizontal, a small keel between them.
The calyx surrounding the base is light green to greenish-white, the lobes awl-like and half or more as long as the tube, and all covered in white, appressed hairs. Flowers are short-stalked and droopy.
Leaves and stems:
Leaves are alternate, compound with 11 to 31 leaflets, up to about 6 inches long. Leaflets are 3/8 to 1 1/3 inches long, narrowly lance-elliptic to linear, rounded or blunt at the tip, roughly hairy on the underside, hairless on the upper surface, and fringed with hair around the edges.
Where the compound leaf meets the stem is a pair of leafy appendages (stipules), ¼ to 1/3 inch long, triangular to nearly diamond-shaped with a sharply pointed tip and joined together around the stem. Stems are multiple from the base, erect to spreading, branched, angled to round in cross-section, often red especially at the base, and variously covered in short, appressed hairs.
Fruit:
Fruit is a drooping, smooth, linear-oblong, flattened, 1-chambered pod up to 1½ inches long, with the remains of the style forming a “tail” at the tip.
Seeds are kidney-shaped, 2 to 3 mm long and wide, brown.
Notes:
Cream Milkvetch is a western species, only recorded once in Minnesota, in 1895 near Pipestone. It is considered “historical” in the state and may yet be rediscovered some day, but suitable habitat is limited in the state. Where it is more abundant it's found in prairies, roadsides, badlands, gullies, and open woods, in clay or chalky, alkaline soils rich in selenium. We encountered it in the Badlands of South Dakota. Cream Milkvetch is similar to the common Canada Milkvetch (Astragalus canadensis), which has stalkless flowers more tightly packed, creamy to greenish and mostly spreading not droopy, fruit is an erect 2-chambered pod, and is rhizomatous where Cream Milkvetch has a taproot. Also similar is Cooper's Milkvetch (Astragalus neglectus), which has 10 to 20 stalkless flowers per cluster that barely rise above the attending leaf, has stipules not joined around the stem, and the fruit is an erect, oval, inflated pod about half as broad as long. There are 3 recognized varieties of Astragalus racemosus, though their distinguishing characteristics are not well-documented; var. racemosus is the most common and the species once found in Minnesota.
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More photos
- Cream Milkvetch plant
- Cream Milkvetch plant
- Cream Milkvetch plants
- a bushy plant prior to flowering
- garden-grown Cream Milkvetch
- purplish flowers ©Pamela Trewatha
- Cream Milkvetch habitat ©Pamela Trewatha
Photos by Katy Chayka and Peter M. Dziuk taken in South Dakota and in a private garden. Photos courtesy Pamela Trewatha, Missouri State University, used by permission.
Comments
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