Abstract:

The great morphological variation in staminate flowers makes it favorable for its use as the main criteria for infrageneric classification in the genus Schisandra (Schizandra) Michx. Organogenesis of different kinds of the staminate flowers has been observed under SEM. Combined with other currently available studies, the patterns of morphogenesis of the staminate flowers are categorized into three types: the columnar-torus type, the flattened-torus type, and the spherical-torus type. In the columnar-torus type, the torus of the staminate flower is kept columelliform through out the whole ontogenic process of the flower; this type can be further divided into two subtypes—the sphenantheraceous subtype, with the thecae laterally localized on both sides of the connective of the mature stamen, and the grandifloraceous subtype, instead with the thecae located outward or slightly outward. In the flattened-torus type, the torus of the staminate flower gradually becomes swollen and then flattened in the process of floral development, and forms a pentagonal shield together with the enlarged filaments and connectives of the stamen. The torus of the staminate flower in the spherical-torus type becomes carnified and swollen with the stamen growing into the depressions or cavities of the spherical torus. Among the three types, the columnar-torus one might be the primitive type, from which the other two were derived representing two different evolutionary trends respectively. By analyzing the cause of the morphological variation of the staminate flowers, it is suggested that the evolutionary pressure by the insect eating during pollinating enhanced the drastic differentiation of the morphology of the staminate flowers. In some taxa of the genus, in which the Coleoptera acted as the main pollinating agent, the enlargement of the torus of the staminate flower to form a thick flattened shield or a spheroid might be an adaptive fitness to the phylogenetic decreasing in number of the stamen. The primitiveness in stamen morphology of the Schisandra staminate flowers is also discussed, which might agree with the origin antiquity of the genus. The similarity of its heteropolar 3- or 6-aperturate pollen to the 3-aperturate pollen of Eudicots might result from convergent evolution. In addition, main infrageneric classifications of Schisandra and the systematic p

五味子属雄花的形态发生及其系统学意义
刘 忠¹  路安民^1*  林祁² 潘开玉¹

（1. 中国科学院植物研究所系统与进化植物学开放研究实验室，北京100093;2. 中国科学院植物研究所标本馆，北京100093）

摘要: 在五味子属 (Schisandra (Schizandra)Michx .)中 ,雄花的形态变异极大 ,是属下分类的主要性状。借助扫描电镜 ,全面观察了五味子属几个不同类型雄花的形态发生 ,结合已有的工作 ,首次提出该属雄花的形态建成有 3种类型。 (1)柱托型 (columnar_torustype)。雄花的花托在花形态发生的全过程中 ,保持柱状 ;根据雄蕊成熟时 ,药室着生的方向 ,又可分为两个亚型 :华中五味子亚型 (sphenantheraceoussubtype)和大花五味子亚型 (grandifloraceoussub type) ,前者药室侧向 ,后者药室外向或外侧向。 (2 )平托型 (flattened_torustype)。雄花的花托随花的发育逐渐扁化 ,雄蕊着生于四周而使雄蕊群呈扁平五边形。 (3)球托型 (spherical_torustype)。雄花的花托肉质化膨大 ,雄蕊着生于球状花托上的凹穴内。在此基础上 ,进一步讨论了诸类型间的系统演化关系 ,认为柱托型是原始类型 ;平托型与球托型源自于柱托型 ,它们是柱托型向不同方向演化的结果。分析了雄花形态变异的原因 ,认为昆虫咬食带来的进化压力导致本属雄花形态的高度分化。雄花花托增生膨大变扁平或者呈球状 ,可能是该属植物中以鞘翅目(Coleoptera)昆虫为主要传粉媒介的类群对系统演化上雄蕊数目减少时的适应性变化。讨论了五味子属植物的雄花在雄蕊形态上上的原始性及其所反映的该类群起源的古老性；其异极3 沟或6 沟型花粉与真双子叶植物的3 沟花粉的相似是趋同演化的结果。此外，对五味子属现行的主要分类系统和五味子科的系统位置进行了讨论。
关键词： 五味子属；形态发生；柱托型；平托型；球托型；传粉媒介；系统发育

Key words: Schisandra, organogenesis, columnar-torus type, flattened-torus type, spherical-torus type, pollination media, phylogeny