Acta Scientiarum Polonorum

The investigations on mechanical properties of reed stems face numerous diffi -
culties, because of their anisotropy, heterogeneity, shell-like structure, small lateral dimensions
of stems and huge diversity of species and habitats of origination. Aware of all diffi
culties to cope with, the basic experiment has been conducted, that is the uni-axial tension
test for reed stems, with- and without joints. The strain-stress relation, at tension, displayed
an exponential character, showing material stiffening with the growth of strain. Test results
incline to conclusion, that stem-pieces without joints are equally stiff as pieces with joints,
however, they are twice as strong as the latter. It means, that joints can be perceived as
fragile (in the sense: “brittle”) discontinuity in structure of reed stems. The results of the
test have been put through critical estimate and analysis tending to statistical modelling of
the load-carrying ability of reed stems.