Seed production in European populations of Ludwigia grandiflora
Ludwigia grandiflora (Onagraceae: EPPO A2 List) is a perennial aquatic helophyte native to South and Central America and is invasive in Africa, the USA and the EPPO region. In its invasive range, L. grandiflora spreads by floating propagules. The primary mode of reproduction is asexual, but sexual reproduction is known from the native range, and has occasionally been observed in France and California. To study if Belgian populations of L. grandiflora can reproduce sexually, seed was collected from 18 populations. Seed germination was studied in Petri dishes under a 12/12h light/dark regime and at 14 - 24°C temperature regime in growth chambers. In total, seed from 14 populations germinated with one population showing a 77 % germination rate. Sexual reproduction may promote the long distance dispersal of propagules of L. grandiflora. Seed may be spread via waterflow and water birds. As part of a management plan, populations of L. grandiflora should be controlled before individual plants have the opportunity to form viable seeds. Removing vegetative biomass at the early stage of an infestation and managing the seed bank can help to prevent the establishment and spread of seedlings.
Sources
Delange OC, Minuti G, Stiers I (2024) Germination of the invasive water Primrose Ludwigia grandiflora in Belgium and potential implications for management. Aquatic Biology 198, 103865. https://doi.org/10.1016/j.aquabot.2024.103865.