Li Wen-Juan, Huang Zi-Xuan, Han Meng, Ren Yi, Zhang Xiao-Hui
College of Life Sciences, Shaanxi Normal University, Xi'an, 710062, China.
Key Laboratory of Medicinal Plant Resource and Natural Pharmaceutical Chemistry of Ministry of Education, Shaanxi Normal University, Xi'an, 710062, China.
Protoplasma. 2022 May;259(3):627-640. doi: 10.1007/s00709-021-01687-1. Epub 2021 Jul 11.
The stamens of angiosperms are diverse in number, colour and structure. The morphological and structural changes of stamens show important evolutionary significance for improving pollination efficiency. In Clematis macropetala, the androecium consists of fertile stamens and tepaloid staminodes. However, studies on the developmental features, structures and possible functions of stamens are few. In this study, the stamen ontogeny, micromorphology and nectary structure of C. macropetala were studied by scanning electron microscopy, light microscopy and transmission electron microscopy. The results indicate that the stamens can be divided into four forms according to shape and anther size: tepaloid staminode (St), spatulate staminode (St), linear-spatulate fertile stamen (St) and linear fertile stamen (St). The characteristics of stamen development are similar in the early stage but gradually differentiate in the later stage. St has delayed development and no anther differentiation. St develops abnormally at the early stage of anther differentiation. St and St are fertile, but their anther sizes are different. Nine epidermal cell types were observed in stamens, with only 4 types in St and 6-7 types in St, St and St. Nectary tissue appears on the adaxial side of the filament base. The nectary is composed of only one layer of secretory epidermal cells, which have a large nucleus, dense cytoplasm and well-developed wall ingrowth. Nectar is released through micro-channels in the cuticle of the outer wall. In Ranunculaceae, the staminal nectary is often located on fertile or sterile stamens, and the position, structure and micromorphology of secretory tissues of the stamen within Ranunculales are discussed.
被子植物的雄蕊在数量、颜色和结构上多种多样。雄蕊的形态和结构变化对于提高授粉效率具有重要的进化意义。在大瓣铁线莲中，雄蕊群由可育雄蕊和花瓣状退化雄蕊组成。然而，关于雄蕊发育特征、结构及可能功能的研究较少。本研究通过扫描电子显微镜、光学显微镜和透射电子显微镜对大瓣铁线莲的雄蕊个体发育、微观形态及蜜腺结构进行了研究。结果表明，根据形状和花药大小，雄蕊可分为四种类型：花瓣状退化雄蕊（St）、匙形退化雄蕊（St）、线状匙形可育雄蕊（St）和线状可育雄蕊（St）。雄蕊发育早期特征相似，但后期逐渐分化。St发育延迟且无花药分化。St在花药分化早期发育异常。St和St可育，但花药大小不同。在雄蕊中观察到9种表皮细胞类型，St中只有4种，St、St和St中有6 - 7种。蜜腺组织出现在花丝基部的近轴面。蜜腺仅由一层分泌表皮细胞组成，这些细胞细胞核大、细胞质浓且细胞壁内突发达。花蜜通过外壁角质层中的微通道释放。在毛茛科中，雄蕊蜜腺常位于可育或不育雄蕊上，并对毛茛目中雄蕊分泌组织的位置、结构和微观形态进行了讨论。
