XVI International Botanical Congess

The leaves (Betula nana, Dianthus repens, Pachypleurum alpinum, Polemonium acutiflorum, Polygonum bistorta and Ranunculus borealis) were collected from plants on soils on two contrasting rock types in the Polar Urals of Russia: ultramafic (serpentine) nickeliferous soils and the more widespread schistose soils. It was shown that there was considerable interspecific variation in the structure of the epicuticular wax deposits on the surfaces of leaves but they tended to be less and have a lower density on the leaves of the plants growing on the ultramafics. It was shown, that the leaf laminas were thicker and the cuticle and the outer walls were thinner in the leaves of the ultramafic plants. It is suggested that the observed microscopic differences in the leaf structure represent cryptic serpentinomorphoses in an area where no taxonomically recognised serpentinomorphoses have been reported.