Q. Why did orchids develop in such myriad forms?
A. The approximately 25,000 to 30,000 different species of orchid evolved along with their many pollinators — from bees, wasps and flies, to moths, butterflies, a cricket and even the occasional bird.
Many of the plant’s special shapes accommodate just one pollinator or a closely related group of pollinators. The flower may mimic the female of a pollinating insect, for example.
Orchids make up about 10 percent of all extant flower types, but their genome suggests that they all descended from a common ancestor. These descendants developed a special deck of genetic cards that can be reshuffled to produce many variations of their characteristic flower plan.
The plan involves bilateral symmetry, rather than radial symmetry; protective sepals alternating with petals; and usually a special lower petal, called a lip, that can serve as a landing pad for pollinators.
Scientists say that this strategy is well suited to efficient pollen transfer, and can be adapted through evolution to attract different pollinators.
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