GRASSLANDS. One of the three great cli matic landscape types—deserts, forests, grass lands—into which S'ehimper, in his work on plant geography, divides the world. It is not yet clear ly known what determines the presence of trees or of grasses in a given locality. Schimper, per haps, has the most tenable hypothesis for the origin of grasslands. viz. that they occur in regions where dry winter winds preclude the presence of forests. Since grasses are shallow rooted, they do not require a moist subsoil, such as trees do, and since they are of low stature, they are protected from the desiccating influence of wind. The greatest development of grasslands' is in the temperate zone. and commonly in Con tinental interiors. Ecologically speaking, the pure climatic grasslands of the world are essen tially similar. though the species found in them vary with the country. In different lands, as is well known, they have various names, of which those that have come to be of most im portance to students of phytogeography are prairie, steppe (qq.v.), and pampas. One speaks
of the pampas of Argentina, the prairies of North America, and the steppes of Europe and Asia. In all these, however, the general life conditions are similar, and there is no essential reason for more than one title. A type of forma tion which differs essentially from that just described is the savanna (q.v.), which is inter mediate between forest and grassland, and is located in a transitional climate. Many of the Banos and campus of Northern South America are true savannas, while others are essentially grasslands. In general, savannas are as charac teristic of tropical regions as pure grasslands are of temperate. Again, there are edaphic grass lands, e.g. river meadows and swamps of lake origin. Through the influence of man, many arti ficial grasslands are to be found, e.g. pastures and most meadows. Perhaps edaphic river sa vannas are to he classed here also. See DISTRI BUTION OF PLANTS.