摘要
用扫描电镜研究了龙眼[Euphoria longan(Lour.)Steud.]花的雌雄器官的发育过程。雄蕊较雌蕊发育稍早。花芽开始分化时,靠近原基部位的周围首先形成5个突起,这些突起就是花器最外层萼片的原基,花萼原基出现后数日在萼片突起的内侧,两个萼片之间出现花瓣突起。接着当萼片表面出现少量毛状体时,在花瓣突起时内侧偏平的花原基圆锥体的周围又出现数个突起,这些突起以后会形成雄蕊。萼片长大逐渐覆盖了整个花原基顶部。此时,在花原基中央部位便开始形成雌蕊。雌蕊分化初期先形成一个两边凸起中间凹下的结构,之后,凸起的两端不断向上延伸形成两个半月形的结构。这两个半月形的结构进一步分化,其下部形成子房,上部则形成一个两裂而末端向外卷曲的柱头和花柱。龙眼花有雄雌之分,当雄雌蕊的突起发育至一定阶段时(约在花芽分化后30天时),雄花内的雌蕊发育减慢,而雄蕊则快速发育形成6—8个具有长花丝的花药。在雌花内雌蕊发育正常,花药外观发育也正常,但花丝则不延长。龙眼除雄花和雌花外,还有各种变态花,这种花到了后期器官的发育都很畸型。
The pattern of development of the floral parts of Longan flower was followed using scanning electron microscope.Floral initiation begins with the formation of calyx protrusions around the floral apex.After the calyx protrusions have appeared,the petal primordia at the base of the floral apex start to appear and then followed by the androecium primordia which appear at the periphery of the floral apex.Gynoecium formation begins much later (at about 30 days after floral initiation).In the male flower,androecium develops normally forming anthers and filaments.Anthers also develop in the female flowers' but they are smaller and the filaments much shorter.Gynoecium in the female flower is well developed and when mature it produces a long style,a two-prong-stigma and two ovaries.In the male flower the gynoecium is poorly developed——the style is short and the stigma seldom splits.Ovaries are also poorly developed in the male flower.In addition to male and female flowers.Longan also forms a number of abnormal flowers with poorly developed androecium and gynoecium.Male and female flowers only become apparent at about 40 days after the initiation of flower differentiation. Prior to this it is difficult to know whether a particular developing flower is going ultimately to become a male or female flower.The formation of abnormal flowers also become obvious' at about 40 days after the initiation of flower differentation.
关键词
龙眼
花器官
发育
扫描电镜
Pattern of development of the floral parts of Longan (Euphoria longan (Lour.) Steud)
Male and female flowers
