There are about 1,700 plants species in the tundra biome. Many of these are species from warmer, more hospitable climates that have adapted to life on the sharp edge of the tundra’s cold temperatures, poor soil, scouring winds and short growing season. These hardy specimens have developed a variety of coping mechanisms to survive where Mother Nature is least nurturing.
A lichen is actually a symbiotic organism. A fungus (which cannot perform photosynthesis) brings some algae (which can) into its body and the two cohabit as a pseudo-plant in all the best places, from the rainforest to the bare rocks of the arctic tundra. The growth commonly known as "reindeer moss” isn’t a moss at all, but a lichen (Cladonia spp.).
Mosses are small, low-growing plants that grow as dense mats in moist places. During the growing season, moisture from snowmelt cannot drain because of the permafrost, causing boggy areas highly suitable for mosses. Mosses produce spores, which can survive the long, harsh winters. Calliergon giganteum is a common moss on the tundra.
Sedges are grasslike plants that grow in the same soggy environments that mosses like. Cottongrass (Eriophorum angustifolium) -- which is not a true grass -- grows in clumps and casts its seeds to the winds. Species of the genus Carex are also found on the tundra.
The tundra supports some tussock-forming grasses that grow in clumps to hold tight to the ground and grow by rhizomes, or underground stems. Arctagrostis latifolia (polar grass) and Poa arctica (Arctic bluegrass) show their tundra adaptation in their names.
The most common plant on the tundra is the bearberry (Arctostaphylos uva-ursi), a ground-hugging evergreen that produces bright red berries popular with birds and bears. Ledum groenlandicum, known as Labrador tea, is a low-growing shrub of the tundra used in folk medicine.
Trees don’t grow on the tundra because they can’t handle the poor soil and harsh conditions. However, some species that appear as trees in other biomes are present on the tundra in a prostrate or creeping form, such as dwarf birch (Betula nana) and willow (Salix purpurea).