Marsilea exarata

Marsilea exarata is a water clover described by A. Braun in 1870 that occurs naturally in Western Australia, the Northern Territory, Queensland, New South Wales and South Australia.¹ Marsilea hirsuta var. exarata and Marsilea paradoxa are regarded as synonyms.¹ An overview of aquarium and pond plants lists it among the cultivated water clovers; the genus colonises wet ground and shallow margins of water bodies and survives extended dry periods as a resting stage.²

Whether the plant grown in aquariums really is M. exarata is questionable: the name is widely used in the trade, but water clovers can usually only be identified reliably by the sporocarps of emersed plants.³ A foreground water clover only a few centimetres tall that has been cultivated for decades is sold, for example, as M. crenata or M. exarata, but its fruit characters match neither of the two species.⁴