Floral nectaries are important components of floral architecture and significant taxonomic traits facilitating assessment of relationships between taxa and can contribute substantially to studies on the ecology and evolution of a particular genus. Knowledge of nectary structure and functioning allows better understanding of the mutualistic interactions between the pollinator and the plant. Robinia viscosa var. hartwigii (Hartweg’s locust), planted in many European countries as an ornamental plant and used for recovery of degraded areas and urban arborisation, is a valuable melliferous species often visited by honeybees and bumblebees. The aim of this study was to investigate the microstructure of the floral nectaries of R. viscosa var. hartwigii with the use of light, fluorescence, scanning, and transmission electron microscopes. The photosynthetic nectaries were located on the inner surface of the cup-like receptacle. The components of pre-nectar were synthesised in the chloroplasts of the glandular parenchyma and transported via the conducting elements of the phloem. Nectar was released through modified nectarostomata. Nectar secretion presumably proceeded in the eccrine mode, whereas nectar transport represented the symplastic and apoplastic types. The cuticle on the nectary epidermis surface contained lipids, essentials oils, and flavonoids, while proteins and flavonoids were present in the glandular parenchyma cells. Idioblasts containing phenolic compounds, tannins, and polysaccharides were observed between the glandular parenchyma cells. The location of the nectaries and the mode of nectar production in the flowers of the Hartweg’s locust follow the common location and structure pattern characteristic for the nectaries in some members of the subfamily Papilionoideae and can be a significant taxonomic trait for the genus Robinia and the tribe Robinieae.

中文翻译：

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刺槐花蜜腺的显微结构。hartwigii（凤蝶科，豆科）——一种有价值但鲜为人知的芳香植物

花蜜腺是花卉结构的重要组成部分和重要的分类特征，有助于评估分类群之间的关系，并且可以对特定属的生态学和进化研究做出重大贡献。对蜜腺结构和功能的了解有助于更好地了解传粉媒介和植物之间的互惠互利。刺槐变种。hartwigii (Hartweg's locust)，在许多欧洲国家作为观赏植物种植，用于退化地区的恢复和城市乔木化，是蜜蜂和大黄蜂经常光顾的珍贵的芳香物种。本研究的目的是调查 R. viscosa var. 花蜜腺的微观结构。hartwigii 使用光、荧光、扫描和透射电子显微镜。光合蜜腺位于杯状容器的内表面。前花蜜的成分在腺体薄壁组织的叶绿体中合成，并通过韧皮部的传导元件运输。花蜜是通过改良的 nectarostomata 释放的。花蜜分泌大概以外分泌模式进行，而花蜜运输代表共生和质外体类型。蜜腺表皮表面的角质层含有脂质、精油和类黄酮，而腺实质细胞中存在蛋白质和类黄酮。在腺实质细胞之间观察到含有酚类化合物、单宁和多糖的成虫细胞。