Adaptation..

Tundra plants are small (usually less than 12 inches tall land low-growing due to lack of nutrients, because being close to the ground helps keep the plants from freezing, and because the roots cannot penetrate the permafrost.

Plants are dark in color—some are even red—this helps them absorb solar heat.

Some plants grow in clumps to protect one another from the wind and cold.

The plants growing in clumps help it converse heat

These plants are growing low

Some plants are covered with hair which helps keep them warm.

http://www.mbgnet.net/bioplants/tundra.html