A collaborative approach to collecting native early season milkweeds in California for monarch butterfly habitat restoration

Abstract

Extensive efforts are underway to help restore populations of western monarch butterflies (Danaus plexippus L. [Lepidoptera: Nymphalidae]). In particular, the growing and outplanting of early season native milkweeds (Asclepias L. [Asclepiadaceae]) show tremendous potential as a nectar food source and as host plants for monarch egg laying. California milkweed (Asclepias californica Greene) and heartleaf milkweed (A. cordifolia Benth.) are the earliest emerging native milkweeds near monarch butterfly wintering areas in California, but a lack of seeds has limited their propagation in nurseries. Starting in 2020, we began efforts to identify stands of California and heartleaf milkweeds and bag follicles to protect their seeds until harvest. In subsequent years, we collected seeds of these early season milkweeds, and efforts have yielded hundreds to thousands of seeds that are now being used for propagation by master gardeners and native plant nurseries.