A
cushion plant is a compact, low growing, mat forming
plant that is found in
alpine,
subalpine,
arctic, or
subarctic environments around the world. The term "cushion" is usually applied to
woody plants that grow as spreading mats, are limited in height above the ground (a few inches at most), have relatively large and deep
tap roots, and have life histories adapted to slow growth in a nutrient poor environment with delayed reproductivity and reproductive cycle adaptations. The plant form is an example of
parallel or
convergent evolution with species from many different plant
families on different continents converging on the same evolutionary adaptations to endure the harsh environmental conditions.