The Orchid Family (Orchidaceae)

Charles Darwin, in a letter to Kew’s then Director Joseph Hooker, wrote 'I was never more interested in any subject in my life, than in this of orchids'.

Vanilla (Vanilla planifolia)
(Image: RBG Kew)

About the orchid family

Orchidaceae make up the largest family of flowering plants, with over 26,000 species known and 100 - 200 new species being discovered every year.

Long prized by collectors for their beauty, and threatened by habitat loss, many orchids are now endangered in the wild. International import and export of orchids is carefully controlled; all orchids are listed on Appendix II or higher of the Convention on International Trade in Endangered Species (CITES).

Where they come from

Orchids are found on all continents with the exception of Antarctica, from the Arctic Circle to the Sub-Antarctic islands south of Australia. They can be found from the edges of deserts to humid rainforests. and are only absent from open water and true deserts. Some orchids live on the ground, while the majority grow perched on trees or rocks. A few are lianas (long-stemmed woody vines), such as vanilla (Vanilla planifolia), which grow up shrubs and trees using them for support.

Lady slipper orchid (Cypripedium calceolus) Image: RBG Kew

All shapes and sizes

The smallest orchid is thought to be Bulbophyllum minutissimum, which is only 3–4 mm tall. The largest are probably vanillas, which are lianas and may be 20m or more in length. Some tropical orchids form very large clumps on trees or rocks – Grammatophyllum speciosum plants of several hundred kilograms have been reported from Southeast Asia.

There is no single characteristic that makes an orchid an orchid. Distinctive features of the group include:

the fusion of the male and female organs into a single structure (called the column)
one of the petals is modified to form a landing pad (lip or labellum) for the pollinator
a large number (up to 4 million) of minute seeds produced by each ovary (fruit)
pollen, which is usually bound together to form large clumps (pollinia).

Bee orchid (Ophrys apifera) Image: RBG Kew

In addition, orchids have protocorms, which are not found in any other plant family. This is a small round translucent structure formed after the germination of the seed, and before the development of the seedling plant. This only occurs in nature once the correct fungus (morels, mushrooms and even truffles) has entered the seed.

How orchids are pollinated

Orchids are generally pollinated by insects and in a few cases also birds. While most orchids produce a reward such as nectar to the pollinator for their efforts, a third cheat the pollinator by not producing any reward. This is taken to the extreme in species such as bee orchids (Ophrys), which have flowers that look, feel and even smell like a female bee! As the male bee tries to have its way with the 'female', it inadvertently picks up the pollen.

Did you know?

19th century Britain went crazy for tropical orchids – nurseries sent out orchid hunters to collect plants from the wild and ship them home in miniature greenhouses. At least half perished on the journey. In 1890 a single orchid brought back to England fetched £1500; equivalent to around £96,000 today!

Kew’s work with orchids

Kew has probably the largest team in the world dedicated to the description, cataloguing, research and conservation of orchids. Their subjects range from taxonomy (classification), pollination biology and orchid-fungus interactions to anatomy, biochemistry and DNA profiling. As orchids become more threatened in the wild by over-collection and destruction of their habitats, Kew’s work is becoming ever more important to ensure that every possible opportunity is taken to protect them.

Kew’s orchid collections

Kew has the oldest living orchid collection in existence, dating back over 200 years, and holds around 5,000 species at any one time. The collection is used extensively by Kew scientists and visiting botanists, as well as students, researchers and enthusiasts who travel to Kew from all over the world to view it.

Kew also has the largest and most comprehensive orchid herbarium, with over 440,000 preserved specimens. Our spirit collection of orchid flowers numbers over 32,000 specimens. The Kew DNA bank already contains 2,500 species. Orchid seeds grown in our micropropagation laboratory are distributed to botanic gardens, nurseries, orchid societies and orchid conservation organisations, helping to ensure that endangered species survive in cultivation.

Princess of Wales Conservatory

Orchids at Kew

There is a permanent orchid display in the Princess of Wales Conservatory. Lowland tropical orchids can be found in zone 6, while orchids from higher altitudes and temperate regions occupy zone 7.

Kew Gardens' annual Tropical Extravaganza features stunning displays of thousands of orchids, alongside other tropical flowers such as bromeliads and anthuriums.

More about the work of Kew's orchid team

Further information on the Orchidaceae

Kew's Princess of Wales Conservatory

Kew's orchid research work

Browse a range of books on orchids available from Kewbooks