[Cal-IPC] Invasive: Glyceria declinata (waxy mannagrass) is a perennial grass (family Poaceae). Waxy mannagrass is found in the Central Valley, from Shasta County south to Fresno County. It has invaded deep vernal pools, swales, ditches, and stock ponds. Some reports indicate that it is rapidly spreading in Central Valley vernal pools.
Cal-IPC Rating: Moderate (contributed by Mary Ann Machi)
[www.cabidigitallibrary.org] Europe, Morocco native, Invasive: G. declinata is a perennial grass associated with shallow water. It is native throughout Europe and in Morocco. It has been introduced to, and is invasive in, North America, Australia and New Zealand.
In California, G. declinata has invaded deep vernal pools, swales, ditches and stock ponds, and is reported to be rapidly spreading in California's Central Valley (Cal-IPC, 2012). The invasion has led to a degradation of vernal pool ecosystems, the habitat of many federal and state protected endangered and threatened species (Gerlach et al., 2009), and has also become a problem in rice plantations in Louisiana. (contributed by Mary Ann Machi)
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Information on California plants for education, research and conservation,
with data contributed by
public and private institutions and individuals.
[web application]. 2023. Berkeley, California:The Calflora Database
[a non-profit organization].Available: