Astragalus trichopodus occurs along and close to the coast of southern California, from San Diego northwards to Santa Barbara and beyond. This is one of the taller members of this large genus, up to 3 feet, branching profusely. Stems are covered by short strigose hairs and longer, spreading hairs. The pinnate leaves have a terminal leaflet and from seven to 19 opposite pairs of lateral leaflets, all similar in size, often folded up along the axis.
The inflorescence is a series of fairly open clusters, attached by long, hairy stalks. Flowers, ten to 50 per cluster, are spreading to reflexed; they have a hairy green calyx, divided about a third of its length into triangular lobes, and a creamy-white corolla, the banner petal of which is angled back at around 45 degrees. Fruits are short pods, linear to narrowly elliptic.
There are three varieties of astragalus trichopodus (phoxus, lonchus, trichopodus), differing in the fruit characteristics.