Imagine you are tiny bacteria or a bit of algae whose job it is to colonize the gravel, sand, clay and silt left over after rocks break apart. The life you produce in the mineral soil will make an inviting home for higher-order plants that will colonize the new soil, eventually building an organic soil that is a nurturing home for familiar plants like ferns, bushes and trees.
Now imagine that you’ve only just started colonizing a fresh patch of sand when a bunch of new sand lands on top of you, burying your work. You start again, but the wind blows you away. You try a different place, but a stream of melt-water washes you away. You try again, but the temperature is just too cold. You might start to appreciate why much of the soil in Antarctica is poor. The soils on inland peaks in Antarctica are virtually sterile (lifeless) and the soil in some of the dry coastal areas hosts only the most simple microscopic organisms. The only richly organic soils to be found on Antarctica are in penguin colonies where the penguin droppings mix with the soil.
Consider the lack of good soil along with the extreme climate and you can start to understand why Antarctica doesn’t have very many plants. Antarctica has only 400 species of lichens (for comparison, the state of California has over 1,500 species of lichen), 75 species of mosses, one species of grass, no ferns, no bushes and no trees. The plants that do manage to grow in Antarctica grow very slowly. Only a few species grow taller than 1.25 inches (3 cm).