洋落葵的花部發育及胚珠位置之探討

Abstract

以落葵科的洋落葵（ Anredera scandens Moq.） 為材料，研究其花部發育，並特別著重於雌器的胎座部位，結果顯示，洋落葵的基生胚珠是由花部頂端產生，非由心皮而來，與同科植物落葵相似。由洋落葵之花式圖觀之，基本構造與落葵幾乎相同：同樣具有一枚大苞片、二枚側生苞片、二枚總苞片、五枚花被片、五枚雄蕊、三心皮構成之一枚雌蕊和一基生胚珠。從花部發育的結果兩相比較，洋落葵之總苞片基部與花被片癒合而落葵則為花被片癒合成筒狀，除上述中期發育階段時的癒合情形有差別外，其各花部始原出現順序及各輪的器官數等早期發育非常相似。我們依據花部中期發育階段時的差別，將洋落葵和落葵分置不同族。洋落葵成熟雄蕊之花藥中具有兩型花粉為該屬首次被發現，文中僅就其形態加以描述。

In Taiwan, Anredera scandens is a cultivated and naturalized plant of Basellaceae. We observed the floral development and checked the ovule position in A. scandens by using scanning electron microscopy. The cauline nature of the ovule and the acarpellate origin in A. scandens is similar to Basella rubra. The basal fusion of involucral bracts with tepals in A. scandens and the fusion of tepals into tube in B. alba. is the major difference in midstage of flower development, while the initiation and the numbers of each whorl of floral organs are similar in early developmental stage of both A. scandens and B. alba. We treat A. scandens and B. alba into different tribe of Basellaceae based on the differences in midstage development of flower. The dimorphism of pollen in A. scandens is first reported, and the morphology of both pollens is illustrated.