The Namib grass Stipagrostis sabulicola relies, to a large degree, upon fog for its water supply and is able to guide collected water towards the plant base. This directed irrigation of the plant base allows an efficient and rapid uptake of the fog water by the shallow roots. In this contribution, the mechanisms for this directed water flow are analysed. Stipagrostis sabulicola has a highly irregular surface. Advancing contact angle is 98° ± 5° and the receding angle is 56° ± 9°, with a mean of both values of approximately 77°. The surface is thus not hydrophobic, shows a substantial contact angle hysteresis and therefore, allows the development of pinned drops of a substantial size. The key factor for the water conduction is the presence of grooves within the leaf surface that run parallel to the long axis of the plant. These grooves provide a guided downslide of drops that have exceeded the maximum size for attachment. It also leads to a minimum of inefficient drop scattering around the plant. The combination of these surface traits together with the tall and upright stature of S. sabulicola contributes to a highly efficient natural fog-collecting system that enables this species to thrive in a hyperarid environment.

As organs of photosynthesis, leaves are of vital importance for plants and a source of inspiration for biomimetic developments. Leaves are composed of interconnected functional elements that evolved in concert under high selective pressure, directed toward strategies for improving productivity with limited resources. In this paper, selected basic components of the leaf are described together with biomimetic examples derived from them. The epidermis (the “skin” of leaves) protects the leaf from uncontrolled desiccation and carries functional surface structures such as wax crystals and hairs. The epidermis is pierced by micropore apparatuses, stomata, which allow for regulated gas exchange. Photosynthesis takes place in the internal leaf tissue, while the venation system supplies the leaf with water and nutrients and exports the products of photosynthesis. Identifying the selective forces as well as functional limitations of the single components requires understanding the leaf as an integrated system that was shaped by evolution to maximize carbon gain from limited resource availability. These economic aspects of leaf function manifest themselves as trade-off solutions. Biomimetics is expected to benefit from a more holistic perspective on adaptive strategies and functional contexts of leaf structures.

Aerial roots of orchids are able to absorb atmospheric water (e.g. rain, mist, dew) and to conduct it to the root interior. The water is absorbed by imbibition into a biological porous material, the velamen radicum, which envelops the aerial root and comprises one or two to several layers. The velamen radicum consists of walls of dead cells and shows an intricate structure. In this contribution, the imbibition process was studied in more detail using mathematical principles and by experimental observation of eight orchid species. The process of absorption can be subdivided into two stages. The initial stage is the attachment of a drop to the rough surface. The drop is then imbibed into the layers of the velamen radicum. During imbibition, the contact angle decreases, because the drop remains firmly pinned to the surface. Imbibition times vary widely, due to differences in the porous structure of the considered species. It could, however, be demonstrated that a detailed theoretical study of imbibition for this complex biological material is possible using structural parameters obtained from microscope images. A third aspect which was considered was evaporation out of the velamen radicum. Also here, observations were consistent with modeling results. The velamen radicum, and other tissues involved in water absorption by aerial roots of orchids, represents an intriguing biological material for studying imbibition and flow in porous materials and has probably a high potential for discovering technically interesting features.

Although being recognized as a major force behind speciation in flowering plants, the evolutionary relevance of genome duplication (polyploidization) remains largely unexplored in mosses. Phylogenetic and-genomic insights from the model organism Physcomitrella patens and closely related species revealed that polyploidization, likely via hybridization (allopolyploidization), gives rise to new species within the Funariaceae. Based on the phylogenetic analysis of the nuclear single copy gene BRK1 combined with the measurement of DNA content by flow cytometry, we identified Entosthodon hungaricus as such an allopolyploid species. Together with Physcomitrium pyriforme, Physcomitrium eurystomum and Physcomitrium collenchymatum, which were identified previously as species that likely arose by hybridization, E. hungaricus represents an additional allopolyploid lineage of a species complex that is characterized by convergent sporophyte reduction and a considerable variance in spore sizes. Based on morphological and cytological data from 18 species, we highlight the potential impact of polyploidization on the size of the spores and on sporophyte architecture.

The large distance between peripheral leaf regions and the petiole in large leaves is expected to cause stronger negative water potentials at the leaf apex and marginal zones compared with more central or basal leaf regions. Leaf zone-specific differences in water supply and/or gas exchange may therefore be anticipated. In this study, an investigation was made to see whether zonal differences in gas exchange regulation can be detected in large leaves. The diurnal course of stomatal conductance, g_s, was monitored at defined lamina zones during two consecutive vegetation periods in the liana Aristolochia macrophylla that has large leaves. Local climate and stem water potential were also monitored to include parameters involved in stomatal response. Additionally, leaf zonal vein densities were measured to assess possible trends in local hydraulic supply. It was found that the diurnal pattern of g_s depends on the position within a leaf in A. macrophylla. The highest values during the early morning were shown by the apical region, with subsequent decline later in the morning and a further gradual decline towards the evening. The diurnal pattern of g_s at the marginal regions was similar to that of the leaf tip but showed a time lag of about 1 h. At the leaf base, the diurnal pattern of g_s was similar to that of the margins but with lower maximum g_s. At the the leaf centre regions, g_s tended to show quite constant moderate values during most of the day. Densities of minor veins were lower at the margin and tip compared with the centre and base. Gas exchange regulation appears to be zone specific in A. macrophylla leaves. It is suggested that the spatial–diurnal pattern of g_s expressed by A. macrophylla leaves represents a strategy to prevent leaf zonal water stress and subsequent vein embolism.