On a conference trip to New Zealand in 2018, I was able to finally meet the final member of the invasive Elodea family, or Hydrocharitaceae. In the United States, we already have the invasive hydrilla (Hydrilla verticillata from Asia) and Brazilian elodea (Egeria densa). Not to be undone, we have contributed to worldwide waterweed problems with “North American” elodea (Elodea canadensis, or Canadian waterweed). The final weedy elodeid is African elodea (Lagarosiphon major), which is an invasive weed to New Zealand and Australia. While it is native to tropical Africa, it can form nuisance problems in South Africa. African elodea is not yet found in North America, but vigilance is required to make sure it is not introduced. The strongly recurved leaves are the best identifying feature to differentiate it from the other elodeid species.
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