Oviposition site selection is a crucial component of the habitat selection in dragonflies. The presence of appropriate oviposition plants at breeding waters is considered to be one of the key habitat determinants for species laying eggs endophytically. For example, Lestes macrostigma, a species which is regarded as threatened in Europe because of its highly fragmental distribution, typically prefers to lay eggs in the sea-club rush Bolboschoenus maritimus. However, little is known about how the anatomy and mechanical properties of plant tissues associated with their choice by L. macrostigma females. We examined green shoots of six plant species used by L. macrostigma for oviposition, either in the field (actual oviposition plants) or under experimental conditions (potential oviposition plants), to analyse anatomy and mechanical properties of shoots in a framework of known preference of plant substrates for oviposition. As expected, anatomy of shoots differed between representatives of two plant families, Cyperaceae and Juncaceae, most essentially in distribution of supporting bundles and presence of large aeriferous cavities that may affect egg placing within a shoot. The puncture force of tested plant samples ranged from 360 to 3298 mN, and their local stiffness ranged from 777 to 3363 N/m. We showed that the most preferred by L. macrostigma plant, B. maritimus, had intermediate characteristics of both the stiffness and anatomy parameters of shoot. The bending stiffness of the ovipositor in L. macrostigma was estimated as 1414 N/m that is one of highest values recorded for zygopteran dragonflies so far. The ecological and behavioural implications of plant-choice mechanisms in L. macrostigma are discussed in the context of fragmented areal distribution of this species.