Pollination biology of Theobroma and Herrania (Sterculiaceae), 1: Floral biology
Floral characteristics related to pollination were studied in four species of Theobroma and one species of Herrania (Sterculiacae) in Costa Rica. Anthesis was complete in T. cacao, T. simiarum, T. speciosum, and T. mammosum at 0615 hr following an extended period of floral development throughout the night. Flowers of both T. cacao and Herrania cuatrecusana were fully open by dawn and pollen sacs dehisced throughout the morning hours. Stigma and style receptivity, assessed by hydrogen peroxide tests, were high throughout the morning and early afternoon in T. cacao. Bagged flowers resulted in no fruit-set. When petal ligules were experimentally removed there was no change in rates of flowers abortion or total numbers of aborted flowers, tentatively suggesting that these structures play little or no role in attracting pollinators. Both Theobroma and Herrania flowers possess ultraviolet light reflectance/absorbance patterns which may play a role in pollinator attraction. Uptake of neutral red stain in T. cacao and T. simiarum showed scattered glandular activity on petals and sepals, perhaps indicating location of nectaries or other secretory organs. Conspicuous glandular trichomes on the ovary, on the lower third of the style, and in a conspicuous "basal ring" between petals and sepals (most pronounced and colorful in species other than T. cacao) may be sources of both floral attractant and reward. Differences in floral biology among Theobroma and Herrania species suggest divergence in pollination strategies. The data presented are discussed in terms of plant-pollinator specializations in the New World tropics.
| Main Authors: | , , , |
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| Format: | biblioteca |
| Published: |
1987
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| Subjects: | THEOBROMA CACAO, THEOBROMA SIMIARUM, THEOBROMA SPECIOSUM, THEOBROMA MAMMOSA, HERRANIA, POLINIZACION, FLORACION, ETAPAS DE DESARROLLO DE LA PLANTA, POLINIZADORES, COSTA RICA, |
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| Summary: | Floral characteristics related to pollination were studied in four species of Theobroma and one species of Herrania (Sterculiacae) in Costa Rica. Anthesis was complete in T. cacao, T. simiarum, T. speciosum, and T. mammosum at 0615 hr following an extended period of floral development throughout the night. Flowers of both T. cacao and Herrania cuatrecusana were fully open by dawn and pollen sacs dehisced throughout the morning hours. Stigma and style receptivity, assessed by hydrogen peroxide tests, were high throughout the morning and early afternoon in T. cacao. Bagged flowers resulted in no fruit-set. When petal ligules were experimentally removed there was no change in rates of flowers abortion or total numbers of aborted flowers, tentatively suggesting that these structures play little or no role in attracting pollinators. Both Theobroma and Herrania flowers possess ultraviolet light reflectance/absorbance patterns which may play a role in pollinator attraction. Uptake of neutral red stain in T. cacao and T. simiarum showed scattered glandular activity on petals and sepals, perhaps indicating location of nectaries or other secretory organs. Conspicuous glandular trichomes on the ovary, on the lower third of the style, and in a conspicuous "basal ring" between petals and sepals (most pronounced and colorful in species other than T. cacao) may be sources of both floral attractant and reward. Differences in floral biology among Theobroma and Herrania species suggest divergence in pollination strategies. The data presented are discussed in terms of plant-pollinator specializations in the New World tropics. |
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