This ecozone is bounded to the south by the treeline, a broad ecological division between the taiga forest and the treeless arctic tundra. The treeline is not really a clear line but rather an irregular transition zone. Within the zone, small scattered clumps of stunted spruce trees grow on warmer, sheltered sites. They often appear in dense cushions less than a metre high that help protect them from the worst of winter winds. This form of tree growth is called krummholz, a German word meaning crooked wood.

Low precipitation and extremely low winter temperatures are among the factors that discourage tree growth in this ecozone. The near continuous blowing of cold, dry winds and the presence of permafrost also restrict plant growth. Low shrubs such as Willow, Shrub Birch, and Labrador Tea are well adapted to these conditions. Where soil is sufficiently developed, these plants form vast shrublands interspersed in lower areas with wet sedge meadows and ponds. On the most exposed sites, low shrubs give way to mats of lichens, mosses, and ground-hugging shrubs such as Mountain Cranberry and Least Willow.

Where hummocks, mud boils, patterned ground, and other permafrost-related features are present, interesting ribbons and circles of vegetation result in response to different amounts of moisture or levels of soil disturbance.

Subtle variations in the distribution, abundance and size of plants in the Southern Arctic Ecozone reflect their sensitivity to small changes in microclimate. The resulting tapestry of plants is best appreciated in the autumn when the tundra produces its rich display of reds, oranges, purples, and yellows. Berry picking is also at its best this time of year, when blueberries, cranberries, and bearberries are often found in great abundance.