Corethrogyne filaginifolia (syn. Lessingia filaginifolia) is a species of flowering plant in the daisy family known by the common names Common Sandaster and California Aster. The taxonomy of this plant and certain relatives is currently changing; recently the Corethrogynes have been grouped together under the name Lessingia filaginifolia, and then moved back to genus Corethrogyne as a single species with many synonyms.

It is native to western North America from the southwestern corner of Oregon to Baja California, where it is a common member of many plant communities, including chaparral and woodlands, forests, scrub, grasslands, and the serpentine soils flora.

This is a robust perennial herb or subshrub producing a simple to multibranched stem approaching a meter in maximum length or height. The densely woolly leaves are several centimeters long and toothed or lobed low on the stem and smaller farther up the stem.

The flower cluster is a single flower head or array of several heads at the tips of stem branches. The head is lined with narrow, pointed, purple-tipped phyllaries which curl back as the head matures. Inside are many purple, lavender, pink, or white ray florets and a center packed with up to 120 tubular yellow disc florets. The fruit is an achene with a pappus of reddish bristles on top.

California Aster appears to do best in rocky slopes and sloping rock gardens. They often don't do as well on flat areas. On dry slopes surrounded by rocks, the plant will usually stay beautiful year round. If happy, it will often reseed and pop up in nearby rocky places.

This plant is very drought tolerant if situated properly. It is not tolerant of summer water, which will often kill it after its first year. California Aster is available in nurseries primarily in low-growing, spreading varieties. 'Silver Carpet' is one of the most beautiful and popular.