Astragalus magdalenae E. Greene var. peirsonii
(Munz & J. McBurney) Barneby

Peirson's milkvetch
Fabaceae (Pea Family)


Peirson's milkvetch is an endangered species that occupies mostly dunes and other sandy locations in Anza-Borrego Desert State Park in San Diego Co. and Algodones Dunes in Imperial Co. It blooms from December to April which explains why I didn't find it in bloom until I visited Algodones Dunes in early February. It is a fairly robust more or less erect bushy plant that can grow to 3' in height and has silvery-canescent vegetation. As the picture below shows, the terminal leaflet is not or only obscurely jointed to the midrib of the leaf, and magdalenae is one of only two Astragalus species in which that is the case. Also the few, sparse lateral leaflets are much reduced and well separated. The 5-20 pink-to-purple (often white-tipped) flowers are held in ascending or spreading inflorescences. The seeds are in large single-chambered ovoid-
to-spheric papery bladders. According to the Jepson Manual, it is either an annual or a perennial, and the seeds are the largest of any American species of Astragalus.

Click here for Latin name derivations: 1) Astragalus  2) magdalenae  3) peirsonii.
Pronunciation: as-TRAG-a-lus mag-da-LEE-nee PEER-son-ee-eye.
Click here for Botanical Term Meanings.


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