Plant species in the Hudson Plain follow latitudinal and soil drainage patterns. Where the boreal forests and the tundra merge in the lowlands, vegetation resembles that of the arctic tundra and to a larger degree the taiga transitional forests. Trees here are few and far between.

The treeless areas extend about 30 kilometres south from the coast but stands of trees can penetrate further north where sites are sheltered or better drainage and deeper soil are available. Arctic tundra can be divided into low and high types. This area is largely representative of the low arctic. Wet areas are dominated by tussocks of sedge, Cottongrass and Sphagnum Moss. Dwarf Birch and Willow shrubs are also common. On drier sites, shrubby and the low-lying Lapland Rosebay, Crowberry, Blueberry and Cloudberry take hold. Herbs such as Arctic Aven, Purple and Prickly Saxifrage, and Lousewart are also found.

South of the tundra is a transition zone known as the taiga. In the lowlands, it can be fairly narrow or up to tens of kilometres wide. Open stands of White Spruce dominate drier areas, while low stands of Willow, Black Spruce and Tamarack are common on wetter and more exposed sites.

The low taiga areas are similar to the high boreal forests. The basic components are boreal in nature but growth and productivity are low and forest stands tend to be more open. White Spruce, Black Spruce, Larch, Balsam and Poplar are the most common trees and Willow and Dwarf Birch are typical shrubs. White spruce in association with Reindeer Moss, Caribou Lichen and Crowberry cover the better-drained and elevated areas.