Ecology: Biology of Interaction. V-20. Life Forms of Organisms

V-20. Life forms of organisms A life form is a stable complex of adaptations to a particular way of life. The study of them was begun by Theophrastus, who divided plants into trees, shrubs, and herbs; Alexander von Humboldt described them in more detail. "The morphological convergence of distant taxa can be complete. Even the great Carl Linnaeus fell victim to it and classified the gymnosperm cycad as a monocotyledonous flowering plant - a palm" (M.B. Mirkin, L.G. Naumova, 2005). Vicars (Latin vicarius - deputy, regent) are species belonging to the same life form and occupying similar ecological niches, but inhabiting different geographical regions. Classic examples of vicariance are provided by marsupial and placental mammals, as well as pairs of lizards - iguanas; boas - pythons. An example of a common classification of plant life forms, which allows for comparison of different ecosystems, is the classification by Christen Raunkiær (Fig. V-20.1). His system is based on the characteristics of the location and winter protection of regeneration organs: therophytes - annuals that survive the unfavorable period of the year (winter or drought) in the form of seeds; cryptophytes - perennial plants whose regeneration organs are underground or underwater during winter or drought periods; hemicryptophytes - perennials with regeneration organs located at ground level (most flowering plants); chamaephytes - plants in which the regeneration organs are located slightly above the ground and are protected by bud scales, and in winter are covered by snow, for example, subshrubs; phanerophytes - plants whose buds are located at least 25 cm above the ground and are usually not covered by snow (trees and shrubs). Fig. V-20.1. Classification of plant life forms by C. Raunkiær, based on the position of regeneration buds in winter: phanerophytes (buds high above the ground: trees, shrubs, vines, and epiphytes); chamaephytes (buds above the ground surface); hemicryptophytes (buds near the ground surface); cryptophytes: geophytes (in the ground) and hydrophytes (in water); therophytes (no regeneration buds, survive winter as seeds)