ID Characteristics
This plant is in the Fabaceae - the legume (pea and bean) family.
Indigo bush is a small shrub that grows no more than 5 feet x 5 feet, often less when growing without irrigation. The form is upright to rounded and the lower stems often lack leaves. It can flower from October through March, with fall bloom depending on rainfall and the heaviest flowering in spring.
The alternate leaves are only a half inch long, typically with 5-7, occasionally 9, leaflets (fewer leaflets on leaves near the ends of the stems). The leaflets are covered with silky, shiny silvery-gray hairs that lie close to the leaf surface. There are rounded glands, most easily seen on the underside of the leaflets. You can see the round glands on the leaf immediately to the left of the flower head (click on photo to enlarge). Rubbing the leaf will release a lightly scented oil from the glands.
The flower heads are dense and rounded, about half an inch wide and initially no more than half an inch high. In the photos above and below, you can see all the dense hairs on the sepals.
The flowers lowest in the cluster open first. The upper petal, the banner, is white often with yellow markings. As the flower ages, the banner may become reddish. The 4 lower petals are purplish, some may see the color as pink. As more flowers open, the flower head gradually elongates. The fruit is small, about 1/10 of an inch, and contains only one seed.