Trees cannot grow in the tundra.
Tundra plants do not have deep root systems. They must also be able to survive the climate and low sunlight levels.
Some arctic plants include: Low shrubs, lichens, and mosses. (The tundra biome, par. 4)
Lichens are plants formed by the symbiotic relationship of algae and fungus.
Lichens growing on rocks. (http://www.mc.maricopa.edu/~johnson/online100/images/lichen2.jpg)
Alpine plants are similar to arctic plants and include: Heaths and tussock grasses.
The tundra also has a variety of flowers. (The tundra biome, par. 7)