Diversidad y orígenes de la flora fanerogámica de México.

摘要: The phanerogamic flora of Mexico is estimated at rough 220 families, 2410 genera and 22000 species. highest incidence diversity found along a belt which originates in Chiapas, traverses Oaxaca, continues to central Veracruz on one side Sinaloa Durango the other. Cloud tropical evergreen forests are most diverse per united area; however, absolute numbers species, other vegetation types surpass them. Approximately 10% 52% species endemic Mexico. These figures rise 17% 72% respectively if an ecologically more natural area considered as point reference, although this would extend by about one-third. Endemism pronounced xerophilous scrubs grasslands, level it also high vegetation, with exception forests. The above figure indicate that country has been site origin evolution great number plant lineages: In arid semi-arid zones northern plants have experienced intense evolution, giving way moderately rich distinctive specialized growth forms often unique; The semi-humid regions developed largely from elements exist parts world; considerable these led locally extensive secondary radiation resulting abundant divers flora; The humid areas, especially warm-humid areas east southeast quite varied; yet date, there not much evidence could important center its evolution. An analysis geographical affinities indicates links south four times those north. This fact should not, be interpreted meaning thar such large majority Mexican derived directly south, since good common Central South America must originated or world, Antilles, Africa, Eurasia North America. Available fossil records show basic features present were already well established mid- Tertiary earlier.