龙眼花蜜腺的发育解剖学研究

Study on developmental anatomy of the floral nectary in Dimocarpus longan

对龙眼 Dimocarpus longan L our. 花蜜腺的形态结构、发育过程以及蜜腺的组织化学变化进行了较为系统的研究 ;对花蜜腺结构与泌蜜的关系、泌蜜方式、起源和系统演化等作了初步的探讨 .结果表明 :龙眼的花盘蜜腺位于花托上 ,呈环状环绕在雌雄蕊基部外围 ,花芽分化约 30 d,在雄蕊和花被之间的花托表面 ,蜜腺原基也开始形成 ,由花托表面 2～ 3层细胞脱分化形成居间分生组织发育而来 ;龙眼花蜜腺由分泌表皮和产蜜组织构成 ,属结构蜜腺 ;分泌表皮角质层极薄 ,密布单细胞绒毛 ,未发现有气孔 ;产蜜组织由亚腺细胞、产蜜细胞、油细胞和维管束组成 ;在蜜腺发育过程中 ,产蜜细胞的液泡和多糖物质发生有规律的变化 ;蜜腺的原蜜汁来源于韧皮部 。

The structure and development of longan’s flowers and its floral nectaries were investigated with the help of paraffin techniques. The results of showed that the peculiarities of longan’s flowers and the pattern of its flowers' sex differentiation. In addition, the relation between nectary structure and secretion of nectar, the way of exudation of nectary, and the origin and evolution of floral nectary in longan were also discussed based on the observed results.About 30 days after the initiation, the nectary anlage begins to form, which is located at the surface of receptacle between androecium and perianth. The nectary anlage is developed by the intercalary meristem produced by 2～3 layers on the surface of receptacle. As a kind of structural nectary, the longan’s floral nectary is composed of secretory epidermis and nectariferous tissue. The secretory epidermis on which single cell hairs are distributed is covered with a thin cuticle and no stomas were found on it. The nectariferous tissue is composed of sub nectariferous cells, nectariferous cells, oil cells and vascular bundles. During the developing process, the vacuoles and polysaccharide in nectary change regularly. Nectar which is mainly synthesized with phloem sap is excreted by permeation through the thin cuticle of epidermis.