梨花蜜腺的解剖观察

梨花蜜腺位于子房上部的盘状结构上，属于下位子房上部的花盘蜜腺。蜜腺由分泌表皮和产蜜组织构成。分泌表皮具波纹状角质层，表皮上分布有气孔器。产蜜组织细胞7～10层，其下有5层左右大型薄壁细胞，与来自子房壁的维管束相毗邻。产蜜组织在发育过程中，其细胞中的淀粉粒呈现一定的消长规律。根据其结构及泌蜜前后的多糖物质分析，其原蜜汁来源于子房壁维管束的韧皮部，通过产密组织积聚加工成蜜汁。蜜汁通过气孔和表皮细胞泌出。

Anatomical observation on floral nectary of Pyrus bretschneideri Rehd.

The floral nectary of Pyrus bretscheidert Rehd. located on the surface of tapered disc above infloror ovary, which belonged to the disc nectary above inferior ovary. The nectary was composed of an epidermis and 7～10 layers of nectariferous tissue. The surface of nectary with modified stoma was covered by a thin-cuticle layer with ripple sculpture. About five layers of parenchyma cells under nectariferous tissue was beside the vascular bundles from ovary wall. During the development of nectariferous tissue, the content of starch grains changed regularly. The pre-nectar may be provided by phloem of the ovary wall. Basing on the nectary structure and polysaccharide changes, it was supposed that the pre-nectare was stored in starch grains in nectariferous tissus and was decomposed into soluble sugar which was the main element of the nectar. The nectar was secreted by stoma and epidermls.