Browsing by Subject "kasvianatomia"

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  • Junikka, Leo (Helsingin yliopisto, 2020)
    This dissertation deals with bark morphology and anatomy of the Neotropical members of the family Annonaceae, and formal taxonomy of the genus Oxandra. This mainly pantropical family comprises ca. 2440 species in 109 genera, which belong to the early divergent mangoliids. About one-third of these taxa occur in the Neotropics (few also in N-America), where they contribute a significant part of plant diversity, both in abundance of species and individuals. Members of the family are mainly trees, shrubs and lianas, which are growing predominantly in tropical and subtropical lowland rainforests. The family is monophyletic and can be recognised, in addition to its flowers and fruits, also by its wood and bark, which possess homogenous, distinctive features representative to the family. The first study deals with the macroscopical patterns seen in the outer structures and in the slash (i.e. tangential cut) of the bark and with the terminology used in the bark descriptions. Morphological terminology of barks is critically surveyed in the forest floras and the expert papers and terms are listed for a comparison of bark features. Suggestions are given for a standardised usage of the terms to stimulate a practice of pertinent field notes and to facilitate understanding of the descriptions. The second study concentrates on the structural anatomy of barks in 32 Neotropical genera of Annonaceae. Selected character states at the family and genus levels are scrutinised for identification purposes. Taxonomical and phylogenetic relevances of bark characters are discussed in view of the tentative molecular phylograms. Although the value of the bark characters, in the present understanding, proved to be negligible, some features may help to delineate some genera and even tribes as such. The systematically most distinctive features in bark structure are the sclerification of the phellem cells, the shape of fibre groups and the occurrence of crystals in bark components. A taxonomic revision based on morphological characters is presented for the Neotropical genus Oxandra (Annonaceae). Twenty-seven species are recognised in the genus, which has wide distribution in Central and South America. Two species occur in the Antilles, but the majority are growing in the lowland rainforests of the Amazonia and in the Atlantic rainforest. A few species are flourishing in drier habitats and in nutrient-poor soils. Altogether five species, i.e. O. aberrans, O. bolivarensis, O. rheophytica, O. saxicola and O. unibracteata, are described as new to the science. A special attempt is made to find supportive morphological characters in view of the possible division of the genus, because of the polyphyly uncovered by the earlier phylogenetic analyses (verified by plastid data) in the tribe Malmeeae, in which the genus belongs. Only few morphological characters, i.e. the midrib type of the leaves, the length of stipe of the apocarpous fruits and, less so, geographical distribution pattern of the species, corroborate the evidence of segregation of the genus in two clades found in various phylogenetic studies. However, last preliminary results of nuclear and mitochondrial sequence data show the genus to be monophyletic. More species and more resolutions are needed from plant genomic research to make definitive statements about the status of the genus.
  • Bhat, K. M.; Kärkkäinen, Matti (Suomen metsätieteellinen seura, 1980)
  • Kozubov, G. M. (Suomen metsätieteellinen seura, 1971)
  • Saranpää, Pekka (Suomen metsätieteellinen seura, 1985)
  • Bhat, K. M. (Suomen metsätieteellinen seura, 1980)
  • Elfving, Fredrik ([Helsingfors] : [Elfving], 1879)
  • Bhat, K. M. (Suomen metsätieteellinen seura, 1980)
  • Bhat, K. M.; Kärkkäinen, Matti (Suomen metsätieteellinen seura, 1981)
  • Bhat, K. M.; Kärkkäinen, Matti (Suomen metsätieteellinen seura, 1981)
  • Bhat, K. M.; Kärkkäinen, Matti (Suomen metsätieteellinen seura, 1981)
  • Bhat, K. M.; Kärkkäinen, Matti (Suomen metsätieteellinen seura, 1982)
  • Bhat, K. M.; Kärkkäinen, Matti (Suomen metsätieteellinen seura, 1981)