The biological richness of Mexico is well represented by the enormous number of plant species that can be found here.
Although a detailed study of all vegetation and ecological zones hasn't been completed, there is no doubt that Mexico belongs to floristically most diverse countries in the world.
Some authors rank Mexico third after Brazil and Colombia, and ahead of Indonesia, Australia, Zaire and Madagascar. It is generally accepted that there are in between 20 and 50,000 species of vascular plants growing here. The last estimation of Mexican Institute of Ecology states 26, 000, but is considered low by many scientists.