El Elena S, Remizowa Margarita V, Sokoloff Dmitry D
Department of Higher Plants, Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow, Russia.
Faculty of Biology and Biotechnologies, National Research University Higher School of Economics, Moscow, Russia.
Front Cell Dev Biol. 2020 May 19;8:303. doi: 10.3389/fcell.2020.00303. eCollection 2020.
European species of are amongthe most accessible members of the basal angiosperm grade, but detailed studies using scanning electron microscopy are lacking. We provide such data and discuss them in the evolutionary context. Dorsiventral monopodial rhizomes of bear foliage leaves and non-axillary reproductive units (RUs) arranged in a Fibonacci spiral. The direction of the phyllotaxis spiral is established in seedlings apparently environmentally and maintained through all rhizome branching events. The RUs can be located on dorsal, ventral or lateral side of the rhizome. There is no seasonality in timing of their initiation. The RUs usually form pairs in positions N and N + 2 along the ontogenetic spiral. New rhizomes appear on lateral sides of the mother rhizome. A lateral rhizome is subtended by a foliage leaf (N) and is accompanied by a RU in the position N + 2. We hypothesize a two-step process of regulation of RU/branch initiation, with the second step possibly involving environmental factors such as gravitropism. Each RU has a short stalk, 1-2 scale-like phyllomes and a long-pedicellate flower. We support a theory that the flower is lateral to the RU axis. The five sepals initiate successively and form two whorls as 3 + 2. The sepal arrangement is not 'intermediate' between whorled and spiral. Mechanisms of phyllotaxis establishment differ between flowers and lateral rhizomes. Petal, stamen and carpel numbers are not precisely fixed. Petals are smaller than sepals and form a whorl. They appear first in the sectors of the outer whorl sepals. The stamen arrangement is whorled to chaotic. The merism of the androecium tends to be the same as in the corolla. Flowers with odd numbers of stamen orthostichies are found. These are interpreted as having a non-integer merism of the androecium (e.g., 14.5). Carpels form a whorl in and normally alternate with inner whorl stamens. Sterile second whorl carpel(s) are found in some flowers of
欧洲的[物种名称]是基部被子植物类群中最容易研究的成员之一，但缺乏使用扫描电子显微镜的详细研究。我们提供了此类数据并在进化背景下进行讨论。[物种名称]的背腹单轴根状茎上着生有叶和非腋生繁殖单元（RUs），它们按斐波那契螺旋排列。叶序螺旋方向在幼苗中显然由环境决定，并在所有根状茎分支事件中保持。繁殖单元可位于根状茎的背面、腹面或侧面。其起始时间没有季节性。繁殖单元通常在沿着个体发育螺旋的第N和N + 2位置形成对。新的根状茎出现在母根状茎的侧面。一个侧生根状茎由一片叶（N）支撑，并在N + 2位置伴有一个繁殖单元。我们假设繁殖单元/分支起始的调控过程分为两步，第二步可能涉及重力作用等环境因素。每个繁殖单元有一个短柄、1 - 2个鳞片状叶状结构和一朵长梗花。我们支持花位于繁殖单元轴侧面的理论。五片萼片依次起始并形成3 + 2的两轮。萼片排列并非轮状和螺旋状之间的“中间”形式。花和侧生根状茎中叶序建立的机制不同。花瓣、雄蕊和心皮的数量并非精确固定。花瓣比萼片小，形成一轮。它们首先出现在外轮萼片的区域。雄蕊排列从轮状到混乱。雄蕊群的轮数往往与花冠相同。发现有奇数雄蕊纵列花型的花。这些被解释为具有非整数的雄蕊群轮数（例如，14.5）。心皮在[物种名称]中形成一轮，通常与内轮雄蕊交替。在[物种名称]的一些花中发现有不育的第二轮心皮。
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