Wetlands within the park are dominated by sedges and mosses with grasses, forbs and scattered shrubs. Dominant species in wetlands include the grasses Arctagrostis latifolia, Arctophila fulva and Calamagrostis canadensis, the sedges Carex aquatilis, C. canescens, C. limosa, C. saxatilis, C. utriculata, and several species of Eriophorum (including E. angustifolium, E. russoleum and E. vaginatum).

Shrub species that occur in wetlands include Cassandra (Chamaedaphne calyculata), sweetgale (Myrica gale) and Bog rosemary (Andromeda polifolia). Horsetails (Equisetum palustre and E. fluviatile), spike rush (Eleocharis palustris), and buckbean (Menyanthes trifoliata) are also common and widespread in lowland wetlands. The dominant, widespread wetland species are present throughout Wrangell-St. Elias. However, there are differences in the distribution of less common species in low elevation wetland areas between northern and southern sections of the Park. For instance, the coastal plant Sitka sedge (Carex sitchensis) is dominant in some sites in the Chitina River valley. Likewise, several wetland species that are rare in Alaska such as Eriophorum viridi-carinatum and Tricophorum pumilum are limited to the Chitina watershed within the Park. These taxa have not been found in northern sites. The rare sedge Carex laxa occurs at two sites in the Tanana River drainage in the northern part of the Park but has not been found further south.