Distribution, morphology and habitats ofElatine triandra(Elatinaceae) in Europe, with particular reference to the central part of the continent

Elatine triandra Schkuhr is the most variable and widespread species within the genus Elatine L.; it has been recorded in all continents, except Antarctica, but it is mainly located in Europe. The study is based on an extensive data set of European literature, herbaria and web data that covers the period 1828–2012. The range of the species in Europe is disjunctive, covering the southern and western parts of the Central European Plain and the southern part of the Fennoscandian Shield. At a smaller scale, the species can also be found along some river valleys. In Central Europe many localities, particularly isolated ones in the northern part of the range, are now only historical. From the data set we determined that E. triandra may be best observed between May and October. We found that species records show a near-significant shift since 1828. Depending on the environmental conditions, individuals of the taxon develop as one of two morphs: terrestrial or aquatic. The aquatic morph is characterized b...