Alopecurus rendlei is an annual grass species of the Poaceae family. The species’
north-eastern distribution range includes Luxembourg and the southern part of Belgium.
The species has shown a dramatic decline in the past decade in both countries and in neighbouring
Germany. The aim of the present study was to investigate the characteristics of A.
rendlei populations in Luxembourg and its bordering regions in Belgium, Germany, and
France and to determine whether regions and populations differ in plant morphology and
site ecology. At each survey site plant material from A. rendlei was collected and the species’
population density was calculated. Furthermore, soil samples were taken, and the floristic
composition of the sites overall was analysed. Within the study area, mean density of A.
rendlei plants per population showed extensive variation. The presence of the species could
only be confirmed in half of the known sites, out of which more than 50% were meadows.
In reference to plant morphology, Luxemburgish populations were similar to the Belgian
ones, except for one population in the south of Luxembourg that displayed many similarities
to French populations. In the German population the internodia were shorter than in
the other studied populations. Plant size as well as leaf length and the leaf length-width ratio
increased from Belgium to Luxembourg and France. The conclusions include management
and further research proposals. Based on our results as well as those of further investigations
that are required, the decline of Alopecurus rendlei should be counteracted.