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Although calcareous erosional mountain systems such as those in central Ellesmere Island constitute extremely limiting environments and are sometimes even considered to be totally unvegetated, quantitative analysis of vegetation revealed 156 species. 81 of which were lichens. Although cryptogams of such depauperate landscapes in the Canadian High Arctic have often been overlooked in vegetational studies. it was found that lichens serve as reliable ecological markers, and under the most limiting conditions, 11 species occurred as major dominants. The system also supported 37 bryophytes that in poor sites were dwarfed and sterile but that served as dominants under somewhat better conditions. Thirty-eight species of vascular plants were found, 7 of which were major dominants in less limiting environments. A wide range of both environmental factors and plant communities were found under the marginal conditions of the cliff, slope, and scree system.