Colony-forming, herbaceous perennials with several species providing important habitat and larval food sources for the monarch butterfly while attracting a diverse array of insects.

California milkweeds remain dormant during the colder months. Stems that emerge in April or May bear clusters of small, star-like flowers in summer followed by silky-tailed seeds that are dispersed by wind. A. fascicularis (narrow-leaved milkweed, 1-3’) is the preferred food source for monarch larvae. A. speciosa (showy milkweed, 2-4’) has larger, soft foliage, showier flower clusters, and is also a food source for monarch larvae. A. cordifolia (heart leaf milkweed, 1-2′) has heart-shaped leaves and is also a food source for monarch larvae.