Kaszab Zoltán (szerk.): A Magyar Természettudományi Múzeum évkönyve 64. (Budapest 1972)
Szujkó-Lacza, J. ; Fekete, G.: A survey of the plant life-form systems and the respective research approaches IV. Taxonomic aspects of the life-form protection of the embryonal and meristematic tissues in the dormancy stage
des; they are all perennials with tap-roots, richly ramifying above the soil surface, heterophilous. The greatest number of species occur in the Ponto-Mediterranean region, in Asia Minor, in the Aralo-Caspian area, in the Near and Middle East. Endemic species of a relatively restricted area inhabit the Caucasus and the Aralo-Caspian territory. Grambe maritima advances the furthest westward in the littoral zones. G. tatarica lives in the loess-steppes, also considerably further northwestward from the species centre of the section. Towards the east, C. eordifolia penetrates the farthest into the high mountains of Central Asia, whereas C. kotschyana advances to the high mountain steppes of the Caucasus and Central Asia. C. shungana can be found up to 2500 m.a.s.l. in Turkestan; its area meets nowehere that of the congeners. C. persica, inhabiting the Armenian and Iranian regions of the Elburs range is a similarly disjunct species attaining high elevations. All members of the Sacrocrambe section belong to the Hemicryptophyton life —form. The members of the Leptocrambe section are annuals, ramifying usually not at the base but only in the upper third of the stem. They are restricted to the Mediterranean region and to North and East Africa. C. abyssinica and G. sinuato-dentata live on the steppes of North Africa and the Ethiopian Plateau, as the Therophyton species of shrubby and woody areas (RECHINGER, 1968). G. kralikii grows in the shelter of other species in the desert zone of the Algerian Sahara; C. kiliman•dscharica inhabits the East African steppes and the Kilimanjaro ; G. hispanica and G. filiformis occur equally in the Western and Eastern Mediterranean. The systematic, geographic and life-form separation of the three sections may have occurred in the Tertiary. It is rather striking that the section Sacrocrambe, of a Hemicryptophyton life-form, contains species both of an isolated small area and of extensive range. Contrarily to the general life-form evolution theory, the young Leptocrambe group of Therophyton life-form, containing taxa with relatively special life conditions and of a reduced stature, has a less extensive range. It is worthy of note that the entire cruciferous family possesses some characteristics partly common with the genus Grambe, discussed as its representative above. Thus its genera usually lack recent representatives of their primary arboriform ancestors, and species with a Chamaephyton, and even more with a Heminryptophyton and Therophyton life-form are frequent. The examples put forth (the genera Helleborus and Grambe) also demonstrate the prominency of the habitual characteristics of the life-forms ; this is one of the reasons why they are so frequently used for the differentiation of systematic categories. 6. The evolution of life-forms There are several indirect approaches in studying the evolution of life-forms. By the statistical evaluation of paleobotanical data, HANSEN (1956) approached the problem by a conception and precision hitherto wellnigh unknown in literature. He worked up about 5000 paleobotanical works, and based his inferences on nearly 21 000 species described in about 3300 genera of this literature. He established the life-forms of the species from this material. If a genus contained 25-30 species, he then established the life-form of each taxon; if more, he applied random selection on the basis of the Index kewensis, and determined the life-form of 20-25 species. The life-form spectrum in the several ages, derived at by a consideration of 2004 genera, is as follows :
