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Orchids are some of the most beautiful plants in the world. They make up one of the largest flower families on Earth. There are an estimated 25,000 different kinds of orchid species around the world. Orchids are extremely diverse. They grow in almost every kind of environment. There is even a type of orchid that grows in Alaska! Many orchids grow on trees and bushes. Others grow in soil, sand and rotting leaves. Some orchids are extremely tiny and can only be viewed with a magnifying glass. On the other hand, there are the giant orchids that can grow up to six metres high.

Orchids intrigued the great 19th-century botanist, Charles Darwin. Darwin wanted to understand the rich diversity of these mysterious and alluring plants. He discovered that orchids attract more insects to pollinate them than any other kind of flower. In Europe for example, the fly orchid has petals that look so similar to a bee that male bees attempt to mate with it. The flower also releases scent that attracts the male bees. As a result, the bees pollinate the orchid without ever realising it or getting back anything in exchange!

Darwin was especially fascinated by the orchid species Catasetum. Naturalists classified three sub-species for Catasetum. However, Darwin proved that this type of orchid had three different types of flower - a male, a female and a hermaphrodite. Darwin also discovered that the orchid detected insects and killed them with darts of sticky pollen. Using insects as a source of food allowed the orchid to survive in very poor soil conditions.