Beech (Fagus) is a genus of ten species of deciduous trees in the family Fagaceae, native to temperate Europe, Asia and North America. F. sylvatica is the most commonly cultivated, although there are few important differences between species aside from detail elements such as leaf shape. Beeches may get to as tall as 27 meters and 1.8 meters in width, although usually much smaller. The nuts are edible, though bitter (though not nearly as bitter as acorns) with a high tannin content, and are called beechnuts or beechmast. They often fail to fill in, especially on solitary trees.