Fagus mexicana Fagus mexicana Fagus mexicana, the Mexican beech or haya, is a species of beech endemic to northeastern and central Mexico, where it occurs from southwest Tamaulipas south to Hidalgo and Puebla. It is restricted to high altitude cloud forests in the Sierra Madre Oriental. It is closely related to the American beech "Fagus grandifolia" and is usually treated as "Fagus grandifolia" subsp. "mexicana" (Martínez) E.Murray. "Fagus mexicana" is a deciduous tree, reaching heights of 25–40 m tall and up to 1 m trunk diameter. The leaves are alternate and simple, with a slightly toothed margin, usually smaller than those of
Fagus sylvatica in the buds. In autumn, the tree builds the reserves that will sustain it into spring. Given good conditions, a bud can produce a shoot with up to ten or more leaves. The terminal bud emits a hormonal substance in the spring that halts the development of additional buds. This tendency, though very strong at the beginning of their existence, becomes weaker in older trees. It is only after the budding that root growth of the year begins. The first roots to appear are very thin (with a diameter of less than 0.5 mm). Later, after a wave of above