Marsilea quadrifolia: From Paddy Field Weed to Threatened Species

In this contribution we illustrate a species on the verge of extinction, commonly known as flagship species of temporary wetland agro-ecosystems. Marsilea quadrifolia L., known also as European water clover, is a leptosporangiate pteridophyte typical of aquatic environments, considered a weed of paddy fields of southern Europe; it grows with a creeping rhizome either in submerged or in emerged condition, experiencing heterophylly. The life cycle is carried out by the alternation of generations and species reproduction occurs either with vegetative propagation or with sexual reproduction thanks to sporocarps. The species is ubiquitous in many soils at different levels of pH, preferring mesotrophic to eutrophic shallow waters; it can be found either in natural environments such as lakes and small rivers as well as in an agricultural context, such as paddy fields and ditches. M. quadrifolia is native to Eurasia and has a widespread distribution; it spreads also in America, where it is considered an alien species. For this reason, it is classified as “Least Concern” globally according to the IUCN criteria, however, since its distribution is scattered in Europe, it is assessed as “Vulnerable” and listed as threatened with extinction in most European countries. On the other hand, the species is cultivated in aquaria and has been used for centuries for its ethnobotanical and medicinal properties. Human activities, habitat loss and degradation, excessive water eutrophication, agricultural practices and the presence of alien species are the main threats for the species. Many efforts have been applied to preserve this species, both through in situ reintroduction as well as ex situ techniques, with cultivation in botanical gardens, in vitro propagation as well as spore cryopreservation. However, despite the few successes of these efforts, it’s reappearance in paddy fields could represent a valid opportunity to combine nature conservation and sustainable agricultural practices, offering new possible income for farmers.