Zingiber densissimum flower, pollen and pollinators.

(A): The floral stucture of Zingiber densissimum: TA, tail-like anther crest; S, stigma; A: anther; L: labellum staminode. (B): A fresh flower with the anther appendage manually pushed up to show the secondary pollen presentation mechanism: PA, pollen on the anther; PL, pollen on the labellum staminode; the arrow shows the aggregated pollen chains. (C)-(F): pollen conditions under different treatments, images are to the same scale. (C): Pollen grains that were fixed in FAA solution and observed under a light microscope after stained with aniline blue, with all layers of pollen wall sticking together. (D): A pollen grain observed under a light microscope after water swelling, with all three layers of pollen wall separated. (E): A pollen grain stained with aniline blue and observed under a light microscope after water swelling. (F): The same pollen grain as (E) observed under a fluorescence microscope, with only the layer III reflecting fluorescence. (G): A flower dorsally pollinated by a bee of Macropis hedini. (H): A flower ventrally pollinated by a bee of Amegilla zonata, with a leg of the bee touching the stigma.

(A): 密序姜（Zingiber densissimum）的花部结构：TA为尾状花药冠（tail-like anther crest）；S为柱头（stigma）；A为花药（anther）；L为唇瓣状退化雄蕊（labellum staminode）。(B): 一朵将花药附属物手动推起以展示次生花粉呈现机制的新鲜花朵：PA为花药上的花粉（pollen on the anther）；PL为唇瓣状退化雄蕊上的花粉（pollen on the labellum staminode）；箭头指示聚集的花粉链（aggregated pollen chains）。(C)-(F): 不同处理条件下的花粉状态，所有图像比例尺一致。(C): 经FAA固定液（FAA solution）固定、苯胺蓝（aniline blue）染色后在光学显微镜（light microscope）下观察的花粉粒，其花粉壁各层均相互黏连。(D): 经水合膨胀后在光学显微镜（light microscope）下观察的花粉粒，其花粉壁三层完全分离。(E): 经水合膨胀后用苯胺蓝（aniline blue）染色并在光学显微镜（light microscope）下观察的花粉粒。(F): 与(E)为同一花粉粒，在荧光显微镜（fluorescence microscope）下观察时仅第三层花粉壁可发出荧光。(G): 由赫氏大隧蜂（Macropis hedini）进行背向传粉的花朵。(H): 由带斑无垫蜂（Amegilla zonata）进行腹向传粉的花朵，其蜜蜂的一只足触碰了柱头。