a plant of a genus that comprises the mountain avens

the first and third climatic stages of the late-glacial period in northern Europe, in which cold conditions prevailed and plants of the genus Dryas were abundant. The Older Dryas (about 15,000 to 12,000 years ago) followed the last ice retreat, and the Younger Dryas (about 10,800 to 10,000 years ago) followed the Allerød stage