First confirmed report of Crassula helmsii in Spain
Crassula helmsii (Crassulaceae) is a semi-aquatic plant species which can grow in a number of forms (submerged, emergent or semi-terrestrial) depending on environmental conditions. The species is native to Australia and New Zealand and has been introduced into the EPPO region as an oxygenating plant for aquaria and ponds. In Spain and Portugal, there are previous reports of the presence of C. helmsii, though these reports are uncertain, and in the case of Portugal, considered erroneous by experts. In 2023, floating mats of C. helmsii were detected in a freshwater reservoir (Abegondo-Cecebre) in Galicia, North-West Spain. Further surveys of the reservoir found C. helmsii in its emergent form at ten locations and the submerged form at one site. A number of management methods are available to control C. helmsii, including physical and biological control. Chemical control options are limited in or around waterbodies.
Sources
Fagúndez J, Fernández MA, Balado A, Martínez‑Veiga E, Servia MJ (2024) First record of the semi‑aquatic invasive plant Crassula helmsii in the Iberian Peninsula and its link to potential dispersal drivers. Biological Invasions 26, 1997–2004