The Jaeger’s milkvetch (Astragalus pachypus var. jaegeri) is one of 28 plant species and subspecies named for biologist, educator, and naturalist Edmund Carroll Jaeger, who made his mark on western Riverside County. Dr. Jaeger taught zoology at Riverside City College (RCC) and became Curator of Plants at the Riverside Municipal Museum after he retired from RCC.

Occurrences of Jaeger’s milkvetch were historically found in southwestern Riverside and northern San Diego counties, with more recent observations in northern portions of western Riverside County. This milkvetch occurs on dry ridges and valleys with open sandy or rocky slopes within coastal scrub, chaparral, grasslands, and cismontane woodland at elevations between 1,200 and 3,200 feet. Jaeger’s milkvetch has been found in the Agua Tibia Wilderness, near Vail Lake, along the foothills of the San Jacinto Mountains, and near Aguanga.

Jaeger’s milkvetch is a shrubby perennial that can grow up to 31 inches tall. It blooms from December through June with flowers that vary in color from cream to light yellow. As a member of the pea or legume family, they have many small leaflets on each stem and produce long pea-shaped seed pods that grow up to just over an inch long.

This plant’s ecological role is important for benefiting surrounding plant life by enriching soil fertility through nitrogen fixation, a process that converts nitrogen from the air into a form that plants can use. It also supports pollinators like butterflies and bees and provides a food source for various wildlife. However, as a member of the Astragalus genus, it is also known for its toxicity, which can have an intoxicating effect on some local wildlife and livestock.

Jaeger’s milkvetch is designated as extremely rare by the California Native Plant Society rare plant ranking system. Threats include urbanization and conversion of natural lands to agriculture. Through implementation of the MSHCP, at least 249,440 acres of land supporting suitable habitat for this species are targeted for conservation.

Updated: March 7, 2025