Hibiscus (Hibiscus spp.) are tropical plants. The ancestor species of modern hibiscus can still be found in the world's tropical regions. Most of these ancestor species are not genetically compatible with each other and cannot interbreed. Eight species can cross with each other. These eight -- rosa-sinensis, lilliflorus, schizopetalus, fragilis, genevieve, arnottianus, storckii, kokio -- provided the genetic material for modern hibiscus hybrids.
Pollination in the Wild
Hibiscus can self-pollinate. In other words, pollen from the male parts of the flower ca pollinate the female parts of that same blossom. Hibiscus pollen germinates on the stamen, the male part of the plant. From the stamen, it is transferred to the stigma pads of the pistil, the female parts of the plant. From the pistil, the pollen finds its way to the ovules of the ovary. If the flower is pollinated, a seed pod will develop. The ovary at the base of the flower will swell. Over the course of the next six to 14 weeks, seeds will develop inside it. Eventually the pod will dry and open, releasing about a dozen seeds.
Hibiscus flowers in the wild are pollinated by insects or birds, which transfer the pollen from the stamen to the stigma pads. The type of pollinator varies among species and by region. What remains constant is the way the blossom attracts the pollinators. Hibiscus flowers attract pollinators with their bright colors and a bull's-eye pattern leading to a deep throat. The deep throat and prominent stamen and stigma mean pollinators need to bump the stigma to probe deeper in the flower. Pollen sticks to the pollinator and is transferred to the female parts of either the same flower or sometimes a different flower. Pollinators are rewarded for their pollination efforts by by being allowed to consume the surplus pollen the flowers produce.
Natural pollination sometimes produces hybrids. Most modern hybrids are not the product of pollination in the wild. Hibiscus breeders intentionally cross plants to produce new colors and blossom shapes. For example, if a genetically pure white hibiscus is pollinated by a genetically pure red hibiscus, the result will be seeds that will grow a pink hibiscus. Hybrids rarely breed true when crossed. When breeders have produced the desired traits by cross-pollination, they will generally propagate the hybrid plants by grafting or rooting stems.
Producing hybrids by hand pollination requires that the pollen be transferred mechanically from the stamen to the stigma pads. Breeders will either use a small artist's paintbrush to pick up the pollen and transfer it, or they will pick the flower of one plant and brush the stamen of that plant against the stigma pads of the second plant. When hand pollinating, breeders take special care to determine which varieties of hibiscus produce the best seed pods. These varieties provide the female plant parts for the cross-pollination. Varieties with poorer seed pods provide the pollen.
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