Abstract
Elatine trianda Schkuhr is the most widespread species within the genus Elatine L.; it can be found in all continents, except Antarctica, but the
majority of the locations have been recorded in Europe.
The study is based on an extensive dataset of literature, herbaria and web
data, which spans the period 1828–2012. The range of the species in Europe is
disjunctive; it covers the southern and western parts of the Central European
Plain and the northern shores of the Baltic Sea,
it can also be found along some river valleys. In Central
Europe many localities especially isolated ones in northern part
of the range are historical now. According to the dataset we determined that E. triandra can be observed between May and October. We also found a remarkable
historical decrease of observation time. We found that species observation has
a near significant shift since 1828 that correlates to changes in environmental
variables. Depending on the environmental conditions individuals of the taxon
could develop in two forms: terrestrial and aquatic. The aquatic form is
characterized by twice longer stems and internodes, and also almost twice
longer lamina and petiola. E.
triandra seeds show consistent characteristics both in terms of forms and populations. Our studies show that the best diagnostic feature, in addition to the
construction of flowers, are size, shape and surface structure of seeds. In
Central Europe E. triandra occurs exlusively in communities classified to the
Isoëto-Nano-Juncetea, however the number of species characteristic for the
class and lower syntax in patches decreases from north to south of the
continent.
Keywords
chorology, ephemerophyte,
Isoëto-Nano-Juncetea, phytogeography, vegetation, morphology, maps, phenology
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