Most tundra plants grow flat on the ground, even members of genera that form upright shrubs and trees farther south, with all or part of their stems, leaves, and even flowers densely haired, adaptations against desiccation by the dry winds. Some plants are so low and densely packed that they deserve the name "cushion plants." Flowers of at least some species project well above this mat to be conspicuous to pollinators. Some flowers are parabola-shaped, to reflect sunlight into the center in which (pollinating) insects rest to increase their temperature. Some flowers are heliotropic, facing the sun as it moves for increased heat. In this open, windy habitat, the majority of seeds are wind-dispersed. There are many adaptations to poor soil. Legumes have root nodules with bacteria that transform atmospheric nitrogen to nitrates that can be used by the plants. Some plants grow only around areas of heavy animal use, where nitrogenous wastes serve in lieu of soil nutrients. It is difficult for seeds to become established, so most plants are perennials. Plant growth is slow, so many herbs bloom at very small sizes.
Animal AdapatationsArctic birds are primarily those with long wings and rapid flight, particularly waterfowl, jaegers and shorebirds, which are able to make long migrations and effectively utilize the high productivity of this environment in summer and escape its winter harshness. Some mammals and birds turn white in winter for camouflage, brown again in summer. Insects are best represented by aquatic groups, protected from winter extremes under water. Many utilize glycerol in their body tissues as antifreeze. Large species and individuals of endothermal ("warm-blooded") vertebrates are favored because their low surface-to-volume ratio and short appendages minimizes heat loss. Large predators that can eat a variety of prey sizes are favored, as are generalized herbivores.
