Any flowering plant that grows without intentional human aid. Wildflowers are the source of all cultivated garden varieties of flowers. A wildflower growing where it is unwanted is considered a weed. Thousands of the approximately 250,000 species of flowering plants are wildflowers. Wildflowers can be divided into three categories by location: those found in the tropics and subtropics, those in temperate regions, and those that grow on the summits of mountain chains and in the Arctic and Antarctic.