Myriophyllum rubricaule a parrot’s feather look-alike only known in cultivation
Incorrect labelling and misidentification of plants in trade are widespread and may be caused by negligence or wilful disrespect of regulations. Plants labelled as Myriophyllum ‘brasiliensis’ or M. ‘brasiliense’ have been in the horticultural trade in North-Western Europe for several decades, though their taxonomy has caused confusion among botanists, plant growers and regulators. The name Myriophyllum brasiliense is a synonym of M. aquaticum commonly known as parrot’s feather. However, M. brasiliense in trade and M. aquaticum can be clearly distinguished by both morphological and molecular features. Since 2016, M. aquaticum has been included on the List of invasive alien species of Union concern (EU regulation no. 1143/2014). Following its regulation, M. aquaticum has been fully replaced by Myriophyllum sp. trade name ‘brasiliensis’ in the horticultural trade in Europe. This has resulted in an increase in the number of records of Myriophyllum sp. trade name ‘brasiliensis’ in urban waters as well as in more natural habitats. This is likely a result of inappropriate disposal of garden waste or the deliberate planting of this species in urban waterways and residential areas. To-date, there are records of establishment for the Netherlands, Belgium and Hungary. The ongoing confusion with respect to the epithet ‘brasiliensis’ has prompted researchers at NIVIP (Netherlands Institute for Vectors, Invasive plants and Plant health) a part of NPPO-NL in Wageningen to formally describe this taxon known only in cultivation as a new species: Myriophyllum rubricaule.
Sources
Van Valkenburg JLCH, Duistermaat L(H.), Boer E, Raaymakers TM (2022) Myriophyllum rubricaule sp. nov., a M. aquaticum look-alike only known in cultivation. European Journal of Taxonomy 828, 1–15. https://doi.org/10.5852/ejt.2022.828.1847