Flora and vegetation. – A. Grisebach in the Mexican territory distinguished, from the phytogeographical point of view, three regions: 1. the coastal or zone of the tierras calientes ; 2. the sides of the Atlantic and the Pacific or zone of the tierras templadas ; 3. the plateaus that make up the tierras frías. However, this distinction is too schematic and artificial, because in reality the botanical regions are more than three and they often, in some localities, mix, so as to confuse their characteristic plants.
In the coastal or coastal area we have a band of dunes covered with dense vegetation of modest size: numerous Graminaceae, Asclepiadaceae, Euphorbiacee (several species of the gen. Croton), Convolvulaceae, Leguminosae, Polygonaceae (Coccoloba), Amarantaceae, Acantaceae and some special plants of various families, such as: Martynia diandra, Priva latiifolia, Lamourouxia viscosa, Tournefortia elliptica, Eragrostis Vera crucis, Leersia Gouinii, Trachypogon Gouinii. In the internal part of the dunes there are grasslands with dense carpets of grasses, where there are woods of littoranea Celtis, Mixed with Jatropha, a plane tree (Platanus Liebmanni) very close to the P. occcidentalis, to a species of Quercus and to palm trees of the genera Cocos and Iriartea. Many aquatic plants live in the coastal lagoons (Potamogeton, Salvinia, Marsilia, Pistia, Azolla, Jussiaeua) and Opuntia tuna and Baccharis xalapensis descend to the coastal zone, which are also found in other higher regions of Mexico.
According to topmbadirectory, the tropical forest in the east coast is very close to the beach, while in the west it is further away and to the south it connects with the humid forests of Guatemala and Nicaragua. The forest is preceded by a more or less vast band of shrubs belonging to the Lauraceae (Nectandra), Verbenaceae (Cytarexylon, Clerodendron, Cornutia, Petrea), Euphorbiacee (Croton, Jatropha, Phyllantus) mixed with ferns (Chrysodium vulgare, Lygodeanium); where the forest is in contact with the lagoons there is a mangrove area (Rhizophora,Mangifera, Avicennia nitida and tomentosa).
The forest is made up of distinctly tropical plants; mostly gigantic trees with closely intertwined epiphytes and lianas; here there are Leguminosae (Inga, Lonchocarpus, Poinciana pulcherrima, Canavalia, Diphysa, Bauhinia, Aeschynomene), Anonacee, Mirtacee, Combretacee, species of the genera Ficus, Cecropia, Castilloa, Maclura, Achras, Sideroxylon, Bombax, Guaiacum and then Swietenia mahogany, Haematoxylon Campechianum, H. borealis, Lysiloma candida, Diospyros ebenaster, which supply woods for cabinet making and dyeing. And on these trees there are epiphytes and lianas belonging to the Orchidaceae (Vanilla), Bignoniacee, Polygonaceae and Verbenaceae, especially on the Pacific side.
Moving away from the sea lies the savannah with grasses giants area: Bambusee (Guadua, Chusquea, Merostachys), Panicee (Panicum altissimum and divaricatum ; Gymnothryx distachya and tristachya), Rottboelliacee, large Ciperacee ferns arborescent, Cycads (Dioon, Ceratozamia) Quercus oleoides, Mimosaceae (Mimosa pudica is very abundant).
In the temperate zone several sub-regions can be distinguished: here a large number of species grow: Ferns, Melastomaceae, Apocinaceae, Rubiacee, Gesneracee, Malvaceae, Acantaceae, Solanaceae, Commelinaceae, Nictaginaceae, numerous species of Chamaedorea ; many plants have brightly colored flowers, so much so that their specific indication is given by the attributes splendens, fulgens, etc., and for some of them it seems that even hummingbirds are involved in pollination.
In the lower temperate zone, oaks with persistent leaves grow, in the upper one there are deciduous ones: on these oaks there are parasites (Loranthus) and epiphytes (Piperaceae, Araceae, Orchidaceae, Bromeliads, Begoniacee) and many climbers such as Exogonium purga, Ipomoea orizabensis, Apocinaceae (Echites), Asclepiadaceae (Marsdenia, Gonolobus), Leguminosae, Sapindaceae.
Then there is the agave region: the agave is called the maguey and from it (A. US, A. Atrorubens and other species) are obtained national drinks pulque and mescal. These plants are spontaneous, with the exception of the species from which tequila and mescal are obtained, which is cultivated. Other agaves (A. Lechuguilla, A. Lophanta, A. Univittata) provide fibers for fabrics and ropes. The number of Cactaceae is very considerable and then there are the arborescent lilies of the genera: Yucca, Fourcroya, Dasylirion. Numerous compotes, Vacciniacee, Ericaceae, Crassulacee, Onagracee, Terebintaceae, etc. also grow in this area, the lianas are represented by Dioscorea, Smilax and Tropaeolum and the epiphytes by Tillandsia and Phoradendron. The mountain slopes of central and southern Mexico up to 1800-4000 m. are covered with deciduous and persistent-leaved oak forests with Conifers (Abies Religious, Pinus liophylla, P. Montezumae), which reach gigantic dimensions. Colossal size reaches the Taxodium mucronatum. The juniper bushes continue up to 4200 m. and are then replaced by herbaceous vegetation which at 4800 m. it almost completely ceases: the constituents of this vegetation are generically identical to those of the flora of the high regions of central Europe, only the species are different.
Due to the geographical position of the territory, the Mexican flora consists of different elements, partly coming from the southern United States, partly derived from the flora of the Antilles and tropical America combined with a large number of characteristic species.
According to a by now old statistic by T. Kotschy, out of 7000 plant species in Mexico about 5000 are endemic.
Fauna. – The Mexican fauna, given the geographical position of the country, is made up for a part of elements of the sonorana region, which extends, as well as throughout the southern portion of North America, also in northern Mexico, and for the other half of elements belonging to the Mexican sub-region (of the neotropic region) which includes all of Central America. Among the species of the sonorana region we will notice living in Mexico, among the Mammals, the Mexican deer, the American antelope, the Carolina squirrel, some Hamster, the characteristic Geomids, some species of jumping mice, the curious Romerolagus similar to a rabbit but tailless, living at considerable heights on Popocatepetl, the puma, some species of Canis andVulpes, various shrews, Chiroptera and among the Marsupials the sought-after Opossum. Among the neotropical mammals we will remember some monkeys of gen. Ateles, some bats of the Phyllosomatids group, the jaguar, the ozelot, the Tigrinya cat, various raccoons and martens among the Carnivores. We will also mention among the Ungulates the peccary, various species related to our porcupine among the Rosicanti, some species of Toothless, among which the armadillo and the anteater.
The ornithological fauna includes very few species typical of the region, being made up of olarctic and neotropical species. The Reptiles include the Heloderma of Mexico, a lacertilius that is equipped with sublingual poison glands, varî Ofidî, as well as various species of Saurians from the group of alligators and caimans living in the rivers.
Among the Amphibians we will notice, among the Anurans, large frogs (Rana mugiens) and the Mexican Nototrema, whose eggs develop in a dorsal pocket of the female, and among the Urodeles the Amblystoma mexicanum, whose larva (Axolotl) it has been considered for a long time as an adult form and designated with the name of Siredon pisciformis.
For invertebrates, terrestrial molluscs are very abundant, especially those of fresh water, rich in forms of the Unionidae and Melanidae families. The insects, very numerous, constitute a transitional fauna being represented by olarctic types and therefore similar to Europeans and by neotropical species. Beetles with many species of Longicorns and Scarabeids, Lepidoptera and Orthoptera, of which some species of grasshopper have migratory habits, have considerable development.
