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Abstract [Objective] Trifolium ambiguum Bieb. is an excellent nectar source plant, and understanding the morphological characteristics, tissue structure, and development are critical for proper utilization of T . ambiguum resources. [Methods] Nectar glands of T . ambiguum were collected from five developmental periods and cellular structures were observed in paraffin sections, while the nectar volume and sugar content were determined by capillary method and physiological kits. [Results] (1) Nectar glands were found in the medial base of the filament of nine connate stamens. Distribution of starch grains in nectar production process changed dynamically, belonging to the starch-type nectar gland. (2) The nectar volume of a single floret was (0.394±0.095) μL, and the nectar volume per square meter of grass was (4536.93 ±1319.34) μL. (3) Soluble sugar was the highest in full flowering, 7.978 mg/g. Fructose accounted for the largest proportion of soluble sugar components, more than 50%, and showed a gradual decreasing trend throughout the development of florets. Starch accounted for 81%-82% of the total sugar content, with the highest in full flower, 35.173 mg/g. [Conclusion] The nectar glands of T . ambiguum belong to the androecium nectar glands, consisting of secretory epithelium and nectar-secreting tissues. The raw nectar is supplied by the vascular bundle of the receptacle, processed into nectar by the nectary tissue, and then exits through the stomata of the epidermis. Soluble sugar of the florets is the highest at full flowering, with fructose accounting for the largest proportion. |
