Biogeographical studies of Myriophyllum rubricaule
Myriophyllum species (Haloragaceae) have been popular in trade though some species are invasive or potentially invasive (e.g. M. aquaticum: EPPO List of Invasive Alien Plants, M. heterophyllum: EPPO A2 pest and M. rubricaule: EPPO Alert List). M. rubricaule has been described as only known from cultivation. In 2023, a survey was conducted in Chile and M. rubricaule was recorded in the Araucania region (Cautin Province), and the Los Rios region (Valdivia province). M. rubricaule was found in a temporary nutrient-rich pond in a meadow accompanied by Ludwigia peploides (Onagraceae: EPPO A2 pest) and Hydrocotyle sp. (Araliaceae). In the EPPO region, M. rubricaule is known in Belgium and the Netherlands, where it has escaped from cultivation into the natural environment. It has also been reported from Hungary, and recent iNaturalist records provide locations for Austria, Denmark and Great Britain, where in the case of the latter, the observation is supported by a herbarium collection. M. aquaticum and M. rubricaule are similar in growth habit and preference for nutrient rich marshy habitats and slow flowing waters. Both species regrow from fragments and it is this vigour that has made them popular ornamental plants. In addition, both species show adaptability to the Atlantic climate in Europe. Observations in mesocosms and urban waters in the Netherlands suggest that M. rubricaule remains of more modest dimensions compared to M. aquaticum. A more detailed study on the competitive potential of M. rubricaule is needed in the EPPO region to be able to assess its invasive potential.
Sources
Van Valkenburg J, Duistermaat L, Brundu G, Piet L, Beyer J (2025) Myriophyllum rubricaule Valk. & Duist. Revisited. Botany Letters, https://doi.org/10.1080/23818107.2025.2497323