Comparative Anatomy of Sclerophylls of Mediterranean Climatic Areas

Abstract

Vast territories in the Mediterranean Basin, in southern California, South Africa, southwestern Australia and central Chile are characterized by a physiognomically uniform vegetation. In general terms the predominant vegetation of these regions is termed “xerophytic” according to the concept of Schouv (1822), who so designated plants of dry habitats. Later this concept has been narrowed and precisely defined. Thoday (1933) proposed that the term “xerophyte” should not carry any particular functional or structural implication, but should be used for plants of dry areas, irrespective of their modes of adaptation to such habitats. Walter and Kreeb (1970) state that xerophytes are those plants growing in arid zones and on dry habitats without access to ground water. The aboveground organs of these plants remain alive through the entire year with the exception of the foliage of deciduous species. Excluded from this group are the water accumulating species, the succulents. Nevertheless, the remaining group of xerophytes is still extraordinarily heterogeneous and has been further subdivided. Walter and Kreeb (1970) distinguish the poikilohydrous, malakophyllous, sclerophyllous, aphyllous, and stenohydrous xerophytes.