PMC

Kingdonia uniflora. Heterodichogamy. (A) Flower at early anthesis, with the stigmas higher than the anthers; (B) protandrous flower, with all anthers dehisced and stigmas at lower level than anthers; (C) protandrous flower, with all anthers dehisced and styles reflexed; (D) protogynous flower, with the styles reflexed but the anthers not yet dehisced; (E) protogynous flower, with the anthers beginning to dehisce; (F) two protogynous flowers of a single shoot; the styles of the upper flower beginning to reflex and anthers still undehisced, those of the lower flower reflexed and one stamen dehisced. Scale bars = 2 mm.

Kingdonia uniflora. Heterodichogamy seen with SEM. (A) Protandrous flower with anthers dehisced; (B) enlarged stigma of flower in (A), with turgescent papillae but no pollen; (C) protogynous flower; (D) enlarged part of a stigma of flower in(C), with a germinated pollen grain; (E) flower at the end of anthesis, with all styles reflexed and anthers dried; (F) enlarged stigma of a protogynous flower, with the stigmatic papillae collapsed after anther dehiscence. Scale bars: A, C, E = 1 mm; B, F = 200 µm; D = 10 µm.

Kingdonia uniflora. Diagram of heterodichogamy. (A) Flower at the beginning of anthesis. (B–D) Protandrous flowers: (B) male stage, with stamens dehisced and higher than stigmas; (C) female stage, with stigmas higher than dried anthers; (D) postanthetic flower, with anthers dried and styles reflexed. (E, F) Protogynous flowers: (E) late female stage, with styles reflexed and stamens not yet dehisced; (F) male stage. (G) Young fruit.

Diverse insects visiting flowers of P. wightiana. (A) A halictid bee collecting pollen grains from the central anther in a male-phase flower. (B) A halictid bee seeking nectar on a female-phase flower and touching the stigma. (C) A honey bee contacting the anther on a male-phase flower. (D) A honey bee obtaining nectar on a female-phase flower and touching the stigma. (E) A drone fly obtaining nectar on a male-phase flower and touching the anther. (F) A blow fly on a male-phase flower without contacting the dehiscing anther. (G) A blow fly on a female-phase flower without touching the stigma. (H) An ant sucking nectar without touching the central anther.