Mentougou is known for its big walnuts. A total of 268 out of its 271 villages have walnut trees, and the village has a long history of walnut cultivation dating back 1,200 years. A 300-year-old tree in Yanjiatai village was named the king of all walnut trees. It is 1.5 meters in diameter at breast height and its shade covers 666.7 square meters.