Alpine and subalpine tundra is the low-growing vegetation found in the land above the trees. At this high elevation, the climate is harsh, with searing winds, intense sunlight, and frigid temperatures that limit the growing season. In spite of these conditions, an array of hardy yet fragile wildflowers thrive at elevations above 11,000 feet, including bright blue alpine forget-me-nots, bold yellow sunflowers, and other tundra plants adapted to the weather extremes of the high country. Animals living at this altitude have also adapted to the rugged alpine environment: the flexible hooves of the Rocky Mountain bighorn sheep enable it to climb rocky slopes easily, the yellow-bellied marmot spends most of the warmer months eating to prepare for long winter hibernation, and the pika stores food in underground dens and remains active all winter.