ABSTRACT Valerianaceae provides a model clade for examining diversification in floral shape, especially involving size, bilateral symmetry, asymmetry, and handedness. Fedia species have pink, strongly bilaterally symmetrical corollas while Valerianella species generally have white, near-radially symmetrical corollas. In this study we examine the early floral ontogeny of Valerianella locusta and Fedia graciliflora to compare early growth and developmental traits that may lead to the difference in their mature flowers. Fedia graciliflora and V. locusta inflorescences at varying stages of development were collected and dissected to remove subtending bracts and bracteoles. Images of floral development were taken using a stereomicroscope and a Scanning Electron Microscope. The inflorescence primordium appears to continuously bifurcate as it grows, resulting in an inflorescence with densely packed flowers of varying ages. Flowers of both F. graciliflora and V. locusta initiate petals and stamens simultaneously on a ring-like common primordium. We demonstrate that stamen primordia arise in a spiral pattern, grow faster than other organs, and dominate growth until they are nearly mature. Five petal primordia and two stamens arise in F. graciliflora. In contrast, in V. locusta which has three stamens, four petal primordia initiate, which appear as an open ring-like or U-shaped primordium with a furrow on one side. This likely provides the space for the additional large stamen. Sepal development is not evident and lobes are lacking. Then gynoecium does not begin to develop until the flower bud is nearing maturity. These data provide a framework for future developmental genetic work in these species.

中文翻译：

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Fedia graciliflora 和 Valerianella locusta（缬草科）的花发育

摘要 缬草科提供了一个模型进化枝，用于检查花卉形状的多样化，特别是涉及大小、双侧对称性、不对称性和手性。Fedia 物种具有粉红色、强烈的双侧对称花冠，而 Valerianella 物种通常具有白色、近径向对称的花冠。在这项研究中，我们检查了 Valerianella locusta 和 Fedia graciliflora 的早期花卉个体发育，以比较可能导致其成熟花差异的早期生长和发育特征。收集并解剖处于不同发育阶段的 Fedia graciliflora 和 V. locusta 花序，以去除对着的苞片和小苞片。使用立体显微镜和扫描电子显微镜拍摄花发育的图像。花序原基随着它的生长似乎不断地分叉，导致花序密密麻麻，不同年龄的花朵。F. graciliflora 和 V. locusta 的花在环状共同原基上同时产生花瓣和雄蕊。我们证明雄蕊原基以螺旋模式出现，比其他器官生长得更快，并且在它们接近成熟之前主导生长。五瓣原基和两个雄蕊在 F. graciiflora 中出现。相比之下，在具有三个雄蕊、四个花瓣原基起始的 V. locusta 中，它们表现为一侧有沟的开放环状或 U 形原基。这可能为额外的大雄蕊提供空间。萼片发育不明显且缺乏裂片。然后雌蕊直到花蕾接近成熟才开始发育。