Page:EB1911 - Volume 18.djvu/342

FLORA AND FAUNA] by the Aztec rulers for their own exclusive use. Of the indigenous birds, the turkey has been fully domesticated, and the musk-duck and “chachalaca” are easily reared. Sea-fowl are most numerous on the coasts of Lower California, where certain islands in the arid belt are frequented at night by countless numbers of them. It should be added that many of the migrating birds of North America pass the winter in Mexico.

The insect fauna of Mexico covers a very wide range of genera and species which, like the other forms of animal life, is largely made up of migratory types. No complete study has ever been made of this fauna, but much has been, and is being done by the U.S. Biological Survey and Plant Industry Bureau. To the traveller, the most conspicuous among the Mexican insects, perhaps, are the butterflies, beetles, ants and the myriads of mosquitoes, midges, fleas and chinches. Among the mosquitoes, which are extraordinarily numerous in some of the hot lowland districts, are the species credited with the spread of malarial and yellow fevers. The midges are even more numerous than the mosquitoes. In pleasing contrast to such pests are the butterflies of all sizes and colours, beetles of an inconceivable variety of size, shape and colouration, and ants of widely dissimilar appearance and habits. An interesting species of the last is the leaf-cutting ant (Eciton) which lives in large underground colonies and feeds upon a fungus produced by leaf-cuttings stored in subterranean passages to promote fermentation. These ants will strip a tree in a few hours and are very destructive to fruit plantations. Some of the native trees have developed ingenious methods of defence, one of which is that of attracting small colonies of another species to drive away the marauders. Most destructive, also, are the termites or white ants, whose ravages are to be seen in the crumbling woodwork and furniture of all habitations in the hot zones. Some species build their nests in trees—great globular masses sometimes three feet in diameter, supported on the larger branches, and connected with the ground by covered passages on the outside of the tree. These insects are blind and avoid the light. Bees find a highly congenial habitat in Mexico, and some honey is exported. Spiders are also represented by a large number of genera and species, the most dreaded being the venomous “tarantula” and the savage “mygale.”

Few countries, if any, can present so great a diversity in plant life as Mexico. This is due not only to its geographical position and its vertical climatic zones, which give it a range from tropical to arctic types, but also to its peculiar combination of humid and arid conditions in which we find an extensive barren table-land interposed between two tropical forested coastal zones. These widely divergent conditions give to Mexico a flora that includes the genera and species characteristic of nearly all the zones of plant life on the western continents—the tropical jungle of the humid coastal plains with its rare cabinet-woods, dye-woods, lianas and palms; the semi-tropical and temperate mountain slopes where oak forests are to be found and wheat supplants cotton and sugar-cane; and above these the region of pine forests and pasture lands. Then, there are the mangrove-fringed coasts and the dripping wooded slopes where rare orchids thrive, and above these, on the inland side of the sierra, a treeless, sun-scorched table-land where only the cactus, yucca, and other coarse vegetation of the desert can thrive without irrigation.

For convenience of description, the flora of Mexico may be divided into four great divisions: that of the comparatively barren plateau and the arid coast regions, the humid tierras calientes, the intermediate tierras templadas and tierras frias, and the higher regions of the sierras. The line of demarcation cannot be very sharply drawn, as the zones everywhere overlap each other and local climatic conditions greatly modify plant types. In general, the aspect of the great central plateau north of the Anahuac sierras is that of a dusty, treeless plain. There is but little natural vegetation to be seen—ragged yucca trees, many species of agave and cactus, scrubby mesquite bushes, sage bushes and occasional clumps of coarse grasses. The rainy season completely changes the appearance of these plains, new grass appears, and wheat and Indian corn are cultivated. The rains do not last long, however, and sometimes fail altogether. The most common plants of the Mexican plateau are the agaves, yuccas and cacti, each of which is represented by a number of species. The first is chiefly known in the south by the “magueys,” from which the national drinks “pulque” and “mescal” are extracted. There is some confusion in the specific names of these agaves; the “pulque”-producing plant is usually described as the Agave americana, though A. atrovirens and several others are also credited with the product. The mescal-producing magueys have a thinner leaf and are not cultivated, with the exception of the species producing the “tequila” mescal. The chief value of the agaves, however, is in their fibres, of which a great variety is produced. The principal plateau agaves producing fibre are the A. lechuguilla and A. lophantha and A. univittata of the Jaumave Valley, Tamaulipas, which furnish what may be termed the genuine ixtle fibre. The “tapemete” fibre of western Mexico is credited by Mr E. W. Nelson to the A. vivipara, which is found chiefly in the warmer and lower elevations of the Pacific slope. There are many other fibre-producing agaves, including some of those from which pulque is derived. The cactus is unquestionably the characteristic plant of Mexico. About one

thousand species have been described, a very large percentage of which are to be found on the Mexican plateau.

Explorations by botanists of the United States Department of Agriculture have been made in many localities, in Jalisco, Zacatecas, Michoacan and Tamaulipas, but many years must elapse before the whole ground can be covered. In central and southern Mexico the mountain slopes are forested up to 12,500 to 13,500 ft., juniper bushes continuing up to 14,000 ft. The forests consist of several species of evergreen and deciduous oaks, “oyamel” (Abies religiosa), the arbutus or strawberry tree, the long-leaved Pinus liophylla and the short-leaved “ocote” or Pinus montezumae and the alder, with an undergrowth of elder (Sambucus mexicana), broom and shrubby heath. In the Southern Sierra Madre, the “oyamel” and “ocote” pine are the, giants of the forest, sometimes rising to a height of 100 ft. Oaks are to be found over a wide area and at lower elevations of the sub-tropical zone as well. They are represented by a number of species, and are called “roble” and “encina” by the natives.

In the intermediate zones between the higher sierras and the tierras calientes the flora is very largely composed of species characteristic of the bordering hot and cold regions. Oaks are everywhere common and the “ocote” pine on the Gulf coast is found as far down as 6300 ft. In southern Mexico the pine is found at even lower elevations where the tropical growth. has been destroyed by cultivation and fire. The lower slopes of the sierras, especially those of southern Mexico, are well forested and include an immense number of species. The most common families on the eastern slopes, where the precipitation is heavy, are the magnolias, crotons, mimosas, acacias, myrtles, oaks, plane-trees and bamboos. Palms are common, the chestnut abounds in many places, the cacti are almost as numerous as on the open plateau. On the southern slopes of the Ajusco and other sierras considerable forests of the “ahuehuete” or cypress (Taxodium distichum) are to be found. The “higuerilla”' or castor-oil plant (Ricinus communis) is widely distributed throughout the plateau and the open plains of the lower zones. In some localities the characteristic types of the two climatic extremes, the palm and the pine, are to be found growing side by side.

No brief description can adequately portray the marvellous variety and magnificence of the flora of the tierras calientes. Its forests are not composed of one or a few dominating species, as in the cold temperate zone, but of countless genera and species closely interwoven together—a confused mass of giant trees, lianas and epiphytes struggling to reach the sunlight. This struggle for existence has completely changed the habits of some plants, turning the palm and the cactus into climbers, and even some normal species into epiphytes. Among the more important and conspicuous trees of these tropical forests are mahogany, rosewood, Spanish cedar (Cedrela), cassias, ceibas (Bombax), rubber (Castilloa), palms of many species including the oil-producing Attalea of Manzanillo and Acrocomia of Acapulco, guayacan (Guaiacum), logwood (Haematoxylon campechianum), brazilwood (H. boreale) which should not be confounded with the Brazilian Caesalpinia, palo blanco (Lysiloma candida), the cascalote and divi-divi trees (Caesalpinia Cacalaco and C. coriaria), the “zapote chico” (Achras sapota) from which chicle is extracted, “zapote prieto” (Diospyros ebenaster), wild fig, myrtles, bamboos and many of the types already mentioned in Connexion with the sub-tropical zone. Of the 114 species of trees and cabinet-woods, 17 of oil-bearing plants, and over 60 of medicinal plants and dyewoods indigenous to Mexico, by far the larger part are represented in the tierras calientes. Among the well-known forest products of this zone are arnotto, jalap, ipecacuanha, sarsaparilla, rubber, orchids and a great variety of gums.

Of the economic plants and products of Mexico, the list is surprisingly long and interesting. The cereals, fruits and vegetables of Europe have been introduced and some of them have done well. Wheat is widely cultivated and a considerable part of the population depend upon it for their bread. Indian corn, which is believed to have had its origin in Mexico, also provides food for a large part of the population. “Tunas” or cactus fruit, red peppers, “zapotes” (the fruit of various trees), “arrayan” (Myrtus arayan), “ciruelas” or Mexican plums (Spondias), guavas, “huamuchil” (Pithecolobium dulce), tamarinds, aguacates (Persea gratissima), bananas, plantains, pineapples, grapes, oranges, lemons, limes, granadillas, chirimoyas, mammees (Mammea americana), coco-nuts, cacao, mangoes, olives, gourds and melons, are among the fruits of the country, and rice, wheat, Indian corn, beans, yams, sweet potatoes, onions and “tomatoes” (Physalis) are among its better-known food products. The food of the common people is chiefly made up of Indian corn, beans, red peppers and “tomatoes,” There are about 50 known species of beans (Phaseolus) in Mexico and Central America, and probably a dozen species of red peppers (Capsicum) which are used both in seasoning and in making chili sauce. The “tomato” or “tomatillo” mentioned, is the fruit of the Physalis ixocarpa, sometimes called the “strawberry tomato” and the “Mexican ground-cherry,” which is used with red peppers to make chili sauce. The common potato (Solanum tuberosum), of which wild varieties are found, is not commonly used as a vegetable, but as a flavouring for soups and other dishes. Among other economic plants are the fibre-producing agaves, the best known of which is the A. rigida