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Morphogenesis of the seed cone of Araucaria araucana (Molina) K.Koch and the evolution of the coniferous seed scale
Flora ( IF 1.7 ) Pub Date : 2020-12-01 , DOI: 10.1016/j.flora.2020.151719
Julian Herting , Thomas Stützel

Abstract The incorporation of ontogenetic studies into the study of the evolution of the coniferous ‘seed scale’ over the past decades has yielded novel interpretation of the same. In this context the development of the ‘seed scale’ of Araucariaceae is especially interesting because they have an extensive fossil record dating back to the Mesozoic. Therefore, we report the development of the Araucaria araucana ‘seed scale’ and discuss the evolutionary implications of our findings. We used scanning-electron microscopy to observe and report the development of the ‘seed scale’. We collected the material from October to June, from the bud to the seed cone at pollination. The development of the bract precedes that of the ‘seed scale’. During the development of the latter, the nucellus and the integument arise independently. In later developmental stages, an additional bulge emerges on the distal part of the ‘seed scale’. This additional bulge partly envelopes the ovule. The comparison with development of Podocarpaceae shows striking similarities and from that we infer the homology of the araucariaceous ‘seed scale’ and the epimatium. The comparison with the development of other conifers leads to the novel theory of interpreting the ‘seed scale’ as a modified funiculus. Additionally, we propose that the ‘seed scales’ of all extant conifers can be derived from a Cunninghamia-like morphology.

中文翻译:

Araucaria araucana (Molina) K.Koch 种锥的形态发生和针叶树种鳞的演化

摘要 在过去的几十年里,将个体遗传学研究纳入针叶树“种子尺度”进化的研究中,产生了对其的新解释。在这种情况下,南洋杉科“种子规模”的发展特别有趣,因为它们拥有可追溯到中生代的广泛化石记录。因此,我们报告了南洋杉“种子规模”的发展,并讨论了我们发现的进化意义。我们使用扫描电子显微镜来观察和报告“种子尺度”的发展。我们从 10 月到 6 月收集材料,在授粉时从芽到种锥。苞片的发育先于“种子鳞片”的发育。在后者的发育过程中,珠心和珠被独立出现。在后来的发展阶段,在“种子鳞片”的远端出现一个额外的凸起。这个额外的隆起部分包裹着胚珠。与Podocarpaceae 的发展比较显示出惊人的相似性,由此我们推断出南洋杉的“种子鳞片”和外皮的同源性。与其他针叶树的发展的比较导致了将“种子鳞片”解释为改良的绳索的新理论。此外,我们建议所有现存针叶树的“种子鳞片”都可以从类似杉木的形态中推导出来。与其他针叶树的发展的比较导致了将“种子鳞片”解释为改良的绳索的新理论。此外,我们建议所有现存针叶树的“种子鳞片”都可以从类似杉木的形态中推导出来。与其他针叶树的发展的比较导致了将“种子鳞片”解释为改良的绳索的新理论。此外,我们建议所有现存针叶树的“种子鳞片”都可以从类似杉木的形态中推导出来。
更新日期:2020-12-01
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