Silene acaulis, or moss campion, is a small mountain-dwelling wildflower that is common all over the high arctic and the higher mountains of Eurasia and North America. It is densely tufted, forming domed cushions composed of long shoots, with four or five small green leaves at their apex and many remnants of old leaves below. The leaves are narrow with short stiff hairs on the margin. Numerous pink (or occasionally, white) flowers, seldom more than one on each shoot. Moss campion has a long flowering season and grows primarily in dry, gravelly areas. It displays "compass flowering", developing flowers on the southfacing part of the cushion first, and later on the north side. These cushions capture heat inside, creating warmer conditions when the sun shines.