抄録
The emergence of terrestrial plant life about 500m ys ago is testified by liverwort-like and later moss-like tissue fragments consisting, i.e., of sporopollenin-containing spore walls and waxy cuticles. Macrofossils from the Early Devonian represent low patch-forming land plants that retained bryophyte-characteristics but had branched sporophytes and contained VA-mycorrhiza-like endophytes. Impregnation of cellulosic cell walls by lignin made possible the construction of larger plant bodies exploiting the light/air-space. At the same time the earliest lycophytes appeared, documenting the split of this lineage from the line leading to the remaining green land plants. In the Late Devonian progymnospermous trees appeared in which pseudomonopodial branching was superseded by lateral branching. The acquisition of the seed habit in the seed fern lineage was probably followed by the still problematic transition from the homorhizic pteridophyte organisation to the allorhizic seed plant organisation, the latter also implying axillary branching. During the Carboniferous, in different lineages strange tree constructions evolved, deriving mechanical strength from root mantles, tubular stems, or periderm tissue, yet nearly all of these lineages, at latest by the Permian, succumbed to the shrinking of wetland habitats. The interval from Permian to Mid Cretaceous was mainly a period of variation of the gymnosperm theme, with the rise and demise of several seed fern and other gymnospermous groups. It is most probable that the rise of the angiosperms was mainly due to their flexible developmental system, which permitted, i.e., the evolution of short-lived herbaceous plant bodies and "cheap" seeds. The phenomenon of "unequal split", i.e., the difference in number of taxa between sister groups, leads to the notion that evolutionary success is hardly predictable. Instead, evolutionary success seems to depend on the coincidence between the accumulation of interactive traits in a lineage and a benign constellation of environmental opportunities. This is exemplified by the spread of modern filicalean ferns, which diversified during the Cretaceous in the shadow of the angiosperms.
