Orchids are such beautiful flowers that I never get tired of photographing them. They are also very interesting, especially if one looks at their evolution, ecology and life cycle.

The orchid group is relatively young. Orchids probably evolved from the lilies about 10 or 15 million years ago. In evolutionary terms this is a recent event, especially when compared with the appearance on earth of conifers 300 million years ago.

In spite of their relatively recent origins, orchids have become cosmopolitan species; they are absent only from true deserts and areas of arctic permafrost.

The anatomy and life cycle of orchids are closely tied together. Orchids depend entirely on insects for pollination and their flowers are designed to attract particular species of insects and to facilitate their visits, thereby increasing the probability of an insect visiting two different flowers of the same species within a short period of time. Orchid flowers are built on a pattern of three. They have three petals, two of which are reduced while the third has become patterned and serves as a landing platform for insects. This petal is highly specialised and easily distinguished from the other two.

Orchids evolved when the world was already filled with a large diversity of flowers and animal pollinators. To be successful they had to adapt themselves to be able to attract one species of insect, as this would increase the probability of an insect visiting another flower of the same species, thus carrying the pollen from one flower to another of the same species.

In spite of this strategy many flowers are not fertilised, but to compensate for this, when fertilisation takes place large numbers of very small seeds are produced. The seeds are so small that it is difficult for them to germinate and produce viable plants. They have so little food stored in them that when they germinate they must be colonised by a minute fungus. The fungus lives in only a small part of the seed. If it invaded the whole seed it would kill it, but is prevented from doing so by a fungicide present in the seed.

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