Ren Yi, Li Hong-Fang, Zhao Liang, Endress Peter K
College of Life Sciences, Key Laboratory of Medicinal Plant Resource and Natural Pharmaceutical Chemistry of Ministry of Education, Shaanxi Normal University, Xi'an, 710062 China.
Ann Bot. 2007 Aug;100(2):185-93. doi: 10.1093/aob/mcm106. Epub 2007 Jun 5.
Based on molecular phylogenetic studies, the unigeneric family Eupteleaceae has a prominent phylogenetic position at or near the base of Ranunculales, which, in turn, appear at the base of eudicots. The aim of the present paper is to reveal developmental features of the flowers and to put the genus in a morphological context with other basal eudicots.
Flowers in all developmental stages of Euptelea pleiosperma were collected in the wild at intervals of 7-10 d in the critical stages and studied with a scanning electron microscope.
Remnants of a perianth are lacking throughout flower development. Floral symmetry changes from monosymmetric to asymmetric to disymmetric during development. Asymmetry is expressed in that the sequence of stamen initiation is from the centre to both lateral sides on the adaxial side of the flower but starting from one lateral side and proceeding to the other on the abaxial side. Despite the pronounced floral disymmetry, a dimerous pattern of floral organs was not found. The carpel primordia arise between the already large stamens and alternate with them. Stamens and carpels each form a somewhat irregular whorl. The carpels are ascidiate from the beginning. The stigma differentiates as two crests along the ventral slit of the ovary. The few lateral ovules alternate with each other.
Although the flowers have some unusual autapomorphies (wind pollination, lack of a perianth, pronounced disymmetry of the floral base, long connective protrusion, long temporal gap between androecium and gynoecium initiation, small space for carpel initiation), they show some plesiomorphies at the level of basal eudicots (free carpels, basifixed anthers, whorled phyllotaxis), and thus fit well in Ranunculales.
基于分子系统发育研究，单属科领春木科在毛茛目基部或基部附近具有显著的系统发育位置，而毛茛目又处于真双子叶植物基部。本文旨在揭示领春木花的发育特征，并将该属与其他基部真双子叶植物进行形态学关联。
在关键阶段每隔7 - 10天于野外采集领春木各个发育阶段的花，并用扫描电子显微镜进行研究。
在整个花的发育过程中缺乏花被残迹。花的对称性在发育过程中从两侧对称变为不对称再变为左右对称。不对称表现为雄蕊起始顺序在花的近轴面是从中心向两侧，但在远轴面是从一侧开始并向另一侧发展。尽管花有明显的左右不对称，但未发现花器官的两轮式模式。心皮原基在已经较大的雄蕊之间产生并与它们交替排列。雄蕊和心皮各自形成一个有些不规则的轮状。心皮从一开始就是囊状的。柱头沿着子房腹缝线分化为两个嵴。少数侧生胚珠相互交替排列。
尽管领春木的花有一些独特的自近裔性状（风媒传粉、缺乏花被、花基部明显不对称、长的药隔突出、雄蕊和雌蕊起始之间有长的时间间隔、心皮起始空间小），但它们在基部真双子叶植物水平上表现出一些原始性状（离生心皮、底着花药、轮状叶序），因此很好地归入毛茛目。
