Floral development and floral phyllotaxis in Anaxagorea (Annonaceae)
Floral development and floral phyllotaxis in Anaxagorea (Annonaceae)
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DOI：
10.1093/aob/mcr201
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发表时间：
2011-10-01
期刊：
影响因子：
4.2
通讯作者：
Armstrong, Joseph E.
中科院分区：
文献类型：
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作者：
Endress, Peter K.;Armstrong, Joseph E.
背景与目的：番荔枝属(Anaxagorea)是木兰目热带番荔枝科(奶油苹果科)中的一个大属，但其花的结构在许多方面尚不清楚。本研究旨在通过与番荔枝科其他属和姐妹科番荔枝科植物的比较，分析它们在进化过程中的有趣的花区系特征。方法在野外进行活体染色，用扫描电子显微镜观察液体固定材料，用光学显微镜观察切片系列。结果番荔枝属植物的花叶序与其它番荔枝科植物一样，呈规则的轮生(具有复杂的轮生)，花器官数量较少或中等(雄蕊和心皮较多的植物)，雄蕊和雌蕊的叶序变得不规则。与几乎所有其他番荔枝科植物一样，心皮完全褶皱。在这些特征上，Aaxagorea与姐妹科Eupomatiaceae截然不同，后者具有螺旋状的花叶序和海鞘心皮。扁平的雄蕊和内部退化雄蕊的存在与大多数其他番荔枝科不同，在番荔枝属中可能是半对称的。然而，大多数花科植物的内退化雄蕊是非分泌性的，这与木兰科(真菊科、去甲科、毛花科)中其他科的内退化雄蕊是分泌型的不同。结论番荔枝属植物的花叶序表明番荔枝科植物中没有基本的螺旋模式，复杂的轮生不仅是科的一部分，而且是整个科的一种拟态，并且是不规则的叶系统。这一点以及在木兰科中完全复折的心皮的存在使该科变得同质，并将其与木兰目中最近的近亲区分开来。
Background and Aims Anaxagorea is the phylogenetically basalmost genus in the large tropical Annonaceae (custard apple family) of Magnoliales, but its floral structure is unknown in many respects. The aim of this study is to analyse evolutionarily interesting floral features in comparison with other genera of the Annonaceae and the sister family Eupomatiaceae.Methods Live flowers of Anaxagorea crassipetala were examined in the field with vital staining, liquid-fixed material was studied with scanning electron microscopy, and microtome section series were studied with light microscopy. In addition, herbarium material of two other Anaxagorea species was cursorily studied with the dissecting microscope.Key Results Floral phyllotaxis in Anaxagorea is regularly whorled (with complex whorls) as in all other Annonaceae with a low or medium number of floral organs studied so far (in those with numerous stamens and carpels, phyllotaxis becoming irregular in the androecium and gynoecium). The carpels are completely plicate as in almost all other Annonaceae. In these features Anaxagorea differs sharply from the sister family Eupomatiaceae, which has spiral floral phyllotaxis and ascidiate carpels. Flat stamens and the presence of inner staminodes differ from most other Annonaceae and may be plesiomorphic in Anaxagorea. However, the inner staminodes appear to be non-secretory in most Anaxagorea species, which differs from inner staminodes in other families of Magnoliales (Eupomatiaceae, Degeneriacae, Himantandraceae), which are secretory.Conclusions Floral phyllotaxis in Anaxagorea shows that there is no signature of a basal spiral pattern in Annonaceae and that complex whorls are an apomorphy not just for a part of the family but for the family in its entirety, and irregular phyllotaxis is derived. This and the presence of completely plicate carpels in Anaxagorea makes the family homogeneous and distinguishes it from the closest relatives in Magnoliales.