Summary: Effi Glöckler
Hydrophytes, which are submersed and floating aquatic plants, are adapted to
dynamic processes of the formerly widespread alluvial floodplains. Nowadays the
waterbodies are mostly isolated from the river system and differ substantially re-
garding environmental conditions and dynamics. In this study the distribution of
hydrophytes in the nature reserve Petite Camargue Alsacienne situated on the
former floodplain of the river Rhine was recorded and compared with earlier re-
cords. Also the effect of environmental factors and isolation on composition and
number of hydrophyte species were examined and discussed. 28 vascular hydro-
phytes and 7 Chara species were recorded. No correlation can be shown between
hydrophyte species composition or number of species and environmental variables.
Biotic factors like competition, herbivory and dispersal must therefore play an
important role in structuring hydrophyte communities. Different dispersal mecha-
nisms are discussed, particularly the importance of dispersal by animals and man.
Due to differences in dispersal abilities isolation has different effects on distribu-
tion of hydrophytes. More information on dispersal mechanisms is needed in order
to protect these species.
Submerse und schwimmende Wasserpflanzen, auch als Hy-
drophyten bezeichnet (HARTOG DEN & SEGAL 1964), gehören zu
den gefährdetsten Arten unserer Flora. PHILIPPI (1978) stellte be-