马兜铃属(马兜铃科)花的形态发生研究

对马兜铃属植物北马兜铃(Aristolochia contorta Bge.)花形态发生的扫描电镜观察表明:其花萼在发生时与苞片相似,6枚雄蕊呈4枚先发生、2枚后发生的方式,心皮的发生以6个胎座突出到子房室中为特征,由侵入的侧膜胎座合生为中轴胎座。在胎座发生发育过程中,在花药的腹面各产生一个突起,此突起后来与胎座上端相连,最终发育为合蕊柱裂片。结合文献资料,我们认为北马兜铃的花被与苞片是同源的,其合蕊柱裂片来自于雄蕊,中轴胎座是次生的。

Floral Morphogenesis of Aristolochia L.(Aristolochiaceae)

The floral morphogenesis of the Aristolochia contorta Bge.was observed with a scanning electron microscopy(SEM).In A.contorta,the initiation of the sepal resembles to that of bract,four of the six stamens initiate firstly and the other two slightly later,then six placentas initiate on the ovary wall and intrude into the ovary loculus,finally fuse in the center of the loculus to form an axil placenta.A protuberance appears in ventral base of each anther and is interrupted with the placenta,then the placentas grow upwards and the protuberances expand downwards,which makes these two tissues connect with each other in the following developmental stages.Each of the protuberance forms a gynostemium lobe.To combine with the previous data,we consider that the perianth and the bract are homologous in A.contorta,the gynostemium lobes origin from the stamens,and the axile placentation is formed by the intruded parietal one.