. Bonner zoologische Monographien. Zoology. Ill 100 m n. height 0 m - 100 m Fig. 1: Dimensions of photosynthetically active layers in ocean and land habitats. Modified from VON Wahlert (1978b). (Lycopodiatae) grew up to 40 m; horsetails of the genus Calamites (Equisetatae) had a tree-like habit and reached up to 30 m; both dominated the Carboniferous forests. Extant tree ferns, Alsophila, grow up to 15 m. Both gymnosperms and angiosperms surpass the 100 m-level, the giant sequoias {Sequoiadendron giganteum), and some Eucalytus trees. As other taxa with tree-like representa- tives, th
. Bonner zoologische Monographien. Zoology. Ill 100 m n. height 0 m - 100 m Fig. 1: Dimensions of photosynthetically active layers in ocean and land habitats. Modified from VON Wahlert (1978b). (Lycopodiatae) grew up to 40 m; horsetails of the genus Calamites (Equisetatae) had a tree-like habit and reached up to 30 m; both dominated the Carboniferous forests. Extant tree ferns, Alsophila, grow up to 15 m. Both gymnosperms and angiosperms surpass the 100 m-level, the giant sequoias {Sequoiadendron giganteum), and some Eucalytus trees. As other taxa with tree-like representa- tives, the angiosperms had also primitive forms with herbaceous habits (Gotts- BERGER 1999). In contrast to oceans, where the photosyntetically active layer is limited by the lack of light reaching deeper ocean layers, access to light in terrestrial biotops is completely different. In dense terrestrial vegetation, access to sunlight is posi- tively correlated to the height of plants. During the evolution of land plants the competition for access to light presumably became more and more important in terrestrial biotops. Several key adaptations involving water regime determine the anagenesis of land plants. Due to recent progress in the phylogenetic reconstruction of land plants (Chase et al. 1993; Donoghue 1994; Schmitt 1994b; Endress 1997) the key adaptations related to the water regime can be superimposed to a cladogram (Fig. 2). It shows that most key adaptations in the above mentioned context are posi- tioned on the line of ancestors: a cutin cuticle with low^ pemieability for gases and water enveloping the cellulose wall was already present in liverworts. Adjustable stomata enabled mosses to control water loss via evaporation. Development of specific water-conducting tracheides and lignin as a supporting substance charac- terize cormophytes which are able to take up water from the soil by their roots, to. Please note that these images are extracted from scanned page images that may
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Keywords: ., bookcentury1900, bookcollectionbiodiversity, booksubjectzoology
