Lupinus excubitus is a species of lupine known as the grape soda lupine. Its common name refers to its sweet scent, which is said to be very reminiscent of grape soda. This species and its variants are found in the southwestern United States, especially in California, and in far northern Mexico. The plant is a small shrub with gray-green foliage.

The fan-shaped leaves are each made up of 7 to 10 narrow leaflets. The raceme inflorescence is a tall stalk of rich purple flowers, each with a bright yellow spot. The occasional variant has white flowers. The fruit is a silky legume pod up to 5 centimeters in length containing mottled brown seeds.

There are several named variants of this species, including:

L. e. var. austromontanus - southern mountain lupine

L. e. var. excubitus - grape soda lupine, Inyo bush lupine

L. e. var. hallii - Hall's bush lupine

L. e. var. johnstonii - interior bush lupine

L. e. var. medius - Mountain Springs bush lupine, Colorado bush lupine