<P> There is a wide source of vegetation in the polar region but there are few species in common in the southern and northern polar regions . The Arctic consists of desert and tundra vegetations . The desert vegetation consists of algae, lichens, and mosses . Lichens are the most dominant plants . The ground is bare with patchy cover of lichens and mosses . Flowering plants are also seen but not as common . It only contains 60 species of flowering plants . The Arctic tundra vegetation also consists of lichens and mosses, but it includes shrubs, grasses and forbs as well . The amount of vegetation in the tundra consists on how much sun, or snow cover is in the area . The vegetation in this area may grow as tall as 50 cm (20 in). In the southern part of the Arctic there tend to be more shrubs whereas the northern parts there is less plant cover . In wet areas of the tundra there is tussock grasses and cotton grasses . In moist areas there are short grasses, mosses, willows, and birches . </P> <P> The Antarctic vegetation consists of algae or lichens, and some bacteria and fungi . Mosses and lichens dominate though . The algae and lichens grow where there is moisture, and they hid in cracks to be protected from the wind . The dominate grassland is the tussock . These grasses get to be 2 m (6 ft 7 in) high, so they provide habitat for many mammals . Of the 14,000,000 km (5,400,000 sq mi) of land that makes up Antarctic, less than 2% of it does not have snow or ice . </P> <P> One example of a type of vegetation is a crustose lichen . These lichens are found in moist areas that are hidden from wind . They hide on the surface of rocks in the cracks . They survive off the water that melts from above . These lichen occur in Canada and Alaska, as well as Greenland . These lichens can be red or orange colored and are known to defoliate rocks . </P> <P> There exist many threats to the polar regions . One threat is whaling . Whaling started in the 16th century . People hunted whales to sell the meat . By 1925 the number of whales being killed rose from 14,000 to 40,000 . The International Whaling Commission tried to stop whaling in the 20th century, but was unsuccessful . </P>

Why dont low islands generally have diverse vegetation