In South Africa, some protea flowers are pollinated by mice
Certain proteas hold their blooms near the ground, smell yeasty rather than sweet, and offer nectar laden with xylose that sunbirds refuse. Their customers are Cape spiny mice and elephant shrews, which digest the sugar and gorge on pollen. Around the world, 100,000 to 200,000 animal species carry pollen for flowering plants.
Pollination moves pollen from an anther to a stigma, the step that makes fertilisation and seeds possible. The carriers can be insects, birds, bats, wind, water or the plant itself; self-pollination can happen inside a closed flower. Crosses between species can create hybrids, both in the wild and in breeding programmes. Christian Konrad Sprengel first examined the partnership between flowers and their visitors in the 18th century, and because fruit depends on it, the process matters enormously to farming.
About 80 percent of flowering plants rely on animals. Of some 250,000 flowering plant species, most are served by insects, though around 1,500 species of birds and mammals, including bats, lemurs, possums and squirrels, also transfer pollen. Insect pollination goes back to the age of dinosaurs. Bees dominate, and honey bees and bumblebees show flower constancy, sticking to one species on a trip, which wastes less pollen and avoids clogging stigmas with the wrong kind. Some plants demand special skills: in buzz pollination a bee must vibrate at the right frequency to shake pollen loose.
Flowers advertise to their audience. Day-bloomers for insects tend to be bright with little scent; night-bloomers for bats and moths are pale and heavily perfumed; bird flowers are often red with copious nectar. Some orchids lure bees such as Euglossa cordata by scent, possibly intoxicating them over visits of up to 90 minutes. Reptiles, especially geckos, pollinate mainly on islands where insects and birds are scarce.
After landing, a pollen grain rehydrates, activates and pushes out a tube. In flowering plants two sperm travel down it: one fertilises the egg to form the embryo, the other fuses with polar nuclei to make the endosperm, a double fertilisation that produces a seed. In conifers, ovules sit exposed on cone scales and catch pollen with a sticky pollination drop. Farms near natural habitat attract more pollinators and harvest bigger crops.
Source: Pollination
