Landoltia punctata, a new record for the Netherlands
Landoltia punctata (Lemnaceae) originates from South-Eastern Asia and Australia. It is a small, free-floating plant that has fronds which produce thin roots. The plants can grow into dense mats in stagnant water. It reproduces via vegetative budding and daughter fronds stay attached to mother fronds which gives a cluster-like appearance to the plant. L. punctata can also reproduce sexually by seed, but this does not occur often.
In the Netherlands, the species is often found in water tanks in garden centres and pet shops selling aquarium plants. It is therefore thought to have been introduced as a contaminant of aquarium plants from South-East Asia.
Within the EPPO region, according to the Global Invasive Species Database this species is recorded in Spain and Israel, but has never been recorded as invasive, although it can reproduce and spread rapidly. In the Global Compendium of Weeds, this species is quoted as a ‘Noxious Weed’, an ‘Environmental Weed’, and an ‘Agricultural Weed’. In the Netherlands, it is unlikely that the species will become a nuisance to water management. Additionally, the ecology of this species hardly differs from other indigenous Lemnaceae, and the risk of replacement of a native species is therefore considered very low.
A Global Compendium of Weeds. http://www.hear.org/gcw/alpha_select_gcw.htm
Global Invasive Species Database – Landoltia punctata. http://www.issg.org/database/species/ecology.asp?si=1018;fr=1;sts=;lang=EN
Van Valkenburg J, Pot Roelf (2008) [Landoltia punctata (G. Mey.) D. H. Les ; D. J. Crawford (dotted duckweed), a new record for The Netherlands]. Gorteria 33, 41-50 (in Dutch).