1985/01/01 by K. A. Clayton-Greene, N. J. Collins, T. G. A. Green +1 · 1 citation
Agricultural and Biological Sciences · #Bryophyte Studies and Records #Fern and Epiphyte Biology #Biocrusts and Microbial Ecology
paper · doi:10.1179/jbr.1985.13.4.549
openalex publication_date 1985/01/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/29
The form and distribution of epicuticular wax has been examined by SEM in 35 species of Polytrichaceae. Australian and New Zealand species of Dawsonia have a dense covering of prominent angular platelets (or more irregular wax) on the lamella-margins; Polytrichadelphus magellanicus is very similar. In Polytrichum the epicuticular wax forms an angular to rounded granularity which varies in quantity from species to species; abundant and prominent on the lamella-margins of, e.g., P. formosum and P. commune, hardly detectable in, e.g., P. sexangulare. Pogonatum spp. show sparse to dense angular to rounded granularity on both surfaces, generally more abundant on the upper surface but (with the exceptions of P. grandifolium and (especially) P. urnigerum) less differentiated on the lamella-margins than in Dawsonia or Polytrichum. The parallel between Polytrichum alpinum, Pogonatum grandifolium, P. urnigerum, Psilopilum australe and P. crispulum is noteworthy. Oligotrichum, Batramiopsis, Atrichum and the other species of Psilopilum show either no apparent surface wax or only a fine surface granularity, although their leaves are generally water-repellent, sometimes strongly so. Dendroligotrichum dendroides has almost smooth lamella-margins; D. squamosum has abundant and prominent surface wax.A major function of epicuticular wax in Polytrichaceae is probably to exclude water from the ‘pseudo-mesophyll’ formed by the lamellae, a function supplemented by the inflexed leaf margins of Polytrichum section Juniperifolia. It is best developed on the lamella-margins of the species of Dawsonia, Polytrichadelphus, Polytrichum and Pogonaturn which probably most nearly approach mesophytic vascular plants in their pattern of adaptation.