At the junction of the eastern hardwood forest, southern pine forest and Great Plains biomes, the Ozarks has a diverse plant population. Prickly pear cactus and paw paw trees grow nearly side by side in forests dominated by white oaks. Some species are relicts from the last Ice Age, holding on in cooler pockets around cave mouths while their nearest relatives are hundreds of miles to the north. Others are desert species, left behind on dry rocky glades by similar climate changes. In the springtime, the forest floor blooms with the many "spring ephemerals", the trilliums, bloodroot, trout lilly, jack in the pulpit and others who live out their life during the short interval between the onset of warm weather and the growth of tree leaves that cut off the forest floor from much needed sunshine. In summer, the open areas and roadsides are blooming with pale purple coneflower, butterfly weed, and an array of asters, daisies, wild carrot and others.