Member of the geranium family. The flowers have five pink petals. Each flower produces five seeds attached to a long stalk. As the seeds dry, they detach from the stalk and coil. If they get damp again, they uncoil.

Several species of Erodium occur at Mather Field. Filaree is the most common and can be found in a variety of habitats.

Filaree is an annual plant. It germinates in the fall and blooms during the first warm days of March. It may continue to bloom into May in favorable locations. Sometimes it germinates in the vernal pools before they fill with water. When the pool fills, the Filaree curls up and dies within a week or so.

Filaree can be particularly abundant in the first year or two after a grassland fire. That is because the blackened soil heats up from the sun more than soil with vegetation does. The extra heat tells all the Filaree seeds to germinate. So right after a fire, Filaree is a dominant species. In deeper soils, the Filaree is usually replaced by invasive, non-native annual grasses within a few years.