To provide evidence insight into the phylogenetic position of Itea L., we observed floral ontogeny of Itea yunnanensis Franch. under the scanning electron microscope (SEM) for the first time. The floral phyllotaxis is whorled and floral organogenesis follows centripetal pattern. Sepal initiation is in a two fifths helical order. Petal initiation appears simultaneous, and petals grow at an ordinary rate. The haplostemony of this species arises slightly later than petals but earlier than gynoecium in initiation. Two carpels are free at the early stage of floral ontogeny, but incurve, get closer and become appressed to each other later. Paraffin transverse sections series of gynoecium at anthesis show that two carpels are connate on the ventral side through their entire length. At last, two carpels within the ovary fuse completely, forming two locules separated by a septum, the ventral vascular bundles in two stylar lobes are connected through the parenchyma, and the stigma lobes become fused. These observations are different from those by Bensel and Palser (1975). The gynoecia they described might be not mature, but rather at early developmental stage. We compared floral developmental pattern and floral structure of Itea with its related taxa. In I. yunnanensis petals grow in the way that is different from that of some elated taxa such as Saxifragaceae sensu stricto, Hydrangeaceae, Ribes, Brexia. The developing pattern of gynoecium in I. yunnanensis is similar to that of some members in the Saxifragaceae sensu stricto and Hydrangeaceae. The treatment to raise taxonomic rank of Itea from genus to family, Iteaceae, is supported by our results.
滇鼠刺花的形态发生（鼠刺科）
葛丽萍1,2 路安民1* 潘开玉1
（1. 中国科学院植物研究所系统与进化植物学重点实验室，北京100093；2. 山西农业大学林学院，太谷030801）
摘要： 在扫描电镜下,观察了滇鼠刺(Itea yunnanensis Franch.)花的形态发生.花3朵一束,排成总状花序.花器官为轮状结构,向心发生;花萼以2/5螺旋式相继发生,5个花瓣原基几乎同步地在花萼内侧与其互生的位置发生.雄蕊单轮对萼.当雄蕊发生后,花顶中心的分生组织开始凹陷,成为浅锅状;在其周围出现一个环状的分生组织,随之,2心皮原基产生,进而发育为马蹄形.初期的心皮相互分离,随着进一步发育,心皮内卷,彼此靠近、紧贴,逐渐于腹面合生,形成2室的中轴胎座;花柱的腹维管束通过薄壁组织连通;花期柱头融合,因此该种为合生心皮.对鼠刺属(Itea)及相关类群花发育性状和花结构进行了比较,支持把鼠刺属提升为鼠刺科(Iteaceae)的观点.
关键词： 滇鼠刺；花的形态发生
通讯作者。E-mail: <anmin @ ns.ibcas.ac.cn>
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