Phyllotactic diversity and developmental transitions between phyllotactic patterns are not fully understood. The plants studied so far, such as Magnolia, Torreya or Abies, are not suitable for experimental work, and the most popular model plant, Arabidopsis thaliana, does not show sufficient phyllotactic variability. It has been found that in common verbena (Verbena officinalis L.), a perennial, cosmopolitan plant, phyllotaxis differs not only between growth phases in primary transitions but also along the indeterminate inflorescence axis in a series of multiple secondary transitions. The latter are no longer associated with the change in lateral organ identity, and the sequence of phyllotactic patterns is puzzling from a theoretical point of view. Data from the experiments in silico, confronted with empirical observations, suggest that secondary transitions might be triggered by the cumulative effect of fluctuations in the continuously decreasing bract primordia size. The most important finding is that the changes in the primary vascular system, associated with phyllotactic transitions, precede those taking place at the apical meristem. This raises the question of the role of the vascular system in determining primordia initiation sites, and possibly challenges the autonomy of the apex. The results of this study highlight the complex relationships between various systems that have to coordinate their growth and differentiation in the developing plant shoot. Common verbena emerges from this research as a plant that may become a new model suitable for further studies on the causes of phyllotactic transitions.

叶序模式之间的叶序多样性和发育转变尚不完全清楚。目前研究的植物，如木兰、榧树或冷杉，不适合进行实验工作，而最受欢迎的模式植物拟南芥则没有表现出足够的叶序变异性。已经发现，在常见的马鞭草（Verbena officinalisL.)，一种多年生的世界性植物，叶序不仅在初级转变中的生长阶段之间不同，而且在一系列多个次生转变中沿着不确定的花序轴也不同。后者不再与侧器官特征的变化相关，从理论的角度来看，叶序模式的序列令人费解。来自计算机实验的数据，面对经验观察，表明二次转变可能是由不断减少的苞片原基大小波动的累积效应触发的。最重要的发现是与叶序转变相关的主要血管系统的变化先于顶端分生组织发生的变化。这提出了血管系统在确定原基起始位点中的作用的问题，并可能挑战心尖的自主性。这项研究的结果突出了各种系统之间的复杂关系，这些系统必须在发育中的植物枝条中协调它们的生长和分化。马鞭草作为一种植物从这项研究中脱颖而出，它可能成为适合进一步研究叶序转变原因的新模型。