Munz’s onion is a California threatened plant species, which means that killing or possessing the plant is prohibited by the California Endangered Species Act (CESA). It is also listed as endangered under the federal Endangered Species Act. Munz’s onion is a bulb-forming perennial herb that grows in wet clay soils within grassland and sage scrub habitats. It forms small light colored flowers and blooms from March to May. A plant typically takes three to five years after germination to reach reproductive maturity and produce flowers. Munz’s onion is well adapted to periodic drought and it can survive dry years underground as a bulb.
Munz’s onion is endemic to western Riverside County in grassland, sage scrub, or juniper woodland communities. At the time of this webpage posting, the California Natural Diversity Database reported nineteen occurrences presumed to still exist, though several of those occurrences have not been visited for many years. Current threats to Munz’s onion include urban development, off highway vehicle activities, competition with invasive species for resources and space, climate change, and extirpation due to wildfire. Munz’s onion receives some protection under the Western Riverside County Multiple Species Habitat Conservation Plan (Western Riverside County MSHCP) but it could still be negatively impacted by the effects of development.
Conservation work needs to continue under the Western Riverside County MSHCP to ensure that development does not directly encroach on Munz’s onion habitat. Extant populations should be managed for invasive species encroachment, which presents a range-wide threat. Occurrences on private property need to be conserved, and some populations need to be protected from off-highway vehicle use.
CDFW may issue permits for Munz’s onion pursuant to CESA, and you can learn more about the California laws protecting Munz’s onion and other California native plants. Populations of Munz’s onion occur in CDFW’s Inland Deserts Region. More information is also available from the U.S. Fish and Wildlife Service Species Profile for Munz’s onion.