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Ecology of Stratiotes aloides L. (Hydrocharitaceae) in Eurasia

Efremov, Andrey N., Sviridenko, Boris F., Toma, Cezary, Mesterházy, Attila, Murashko, Yury A.
Flora 2019 v.253 pp. 116-126
Ceratophyllum demersum, Hydrocharitaceae, Lemna trisulca, Pliocene epoch, Potamogeton perfoliatus, Spirodela polyrhiza, Utricularia vulgaris, genetic variation, habitat destruction, macrophytes, population dynamics, population size, seeds, sexual reproduction, soil, surface water, Eurasia, Russia, Southern European region
Stratiotes aloides (Hydrocharitaceae) is a member of hydromacrophyte communities, which are widespread in the waterbodies of Eurasia. In the course of our study, which covered both fieldwork across a large part of the species range as analysis of published sources, we determined that S. aloides is a Pliocene relic showing a boreal-sublatitudinal sub-Eurasian range with a small North American enclave. Its populations are generally quite stable across much of their current range. However, in Western, Central and southern Europe and in the South of European Russia, both local population sizes and area of occupancy of S. aloides populations decline significantly, mainly due to habitat degradation. Regeneration via seed is of particular importance to the plant in extreme conditions, and also for maintaining or increasing the genetic diversity of its populations. Seeds are usually more easily dispersed, across a wider area, than vegetative propagules produced by the plant. Yet, in some populations sexual reproduction is hindered by spatial isolation of the plants of different sexual types and prevalence of gynomonoecious populations. On the other hand, vegetative (clonal) propagation of S. aloides can result in locally-high biological productivity, and extensive occupation of water area by the plant at individual sites.Populations of S. aloides have been found to co-occur with at least 134 other macrophyte species variously present. Highly constant species (present in more than 50% of communities containing S. aloides) include Ceratophyllum demersum, Hydrocharis morsus-ranae, Lemna trisulca, Potamogeton perfoliatus, Spirodela polyrhiza, and Utricularia vulgaris. This species prefers mesotrophic, β-mesosaprobic freshwaters, and detrital, muddy-clayey bottom soils.