| Orchid Information The orchids are a large and diverse family of plants. Orchids or Orchidaceae are in the family of monocot flowering plants in the super order Liliiflorae. Orchids bloom in a range of colour and forms (view some examples in our photo gallery). They also live in a range of habitats (full sun, shade, climbing, on rocks, trees or on the ground). There are however some distinguishing features about the orchids. Some of these features will be highlighted here. | - stamens and pistils (male and female parts) fused to form one structure known as a column
- three petals and three petal-like sepals (collectively called tepals)
- seeds that are tiny and numerous
- lateral symmetry (usually has one different petal that forms a lip or labellum)
- pollen usually bound together in pollinia (a few large masses of pollen within the anther cap)
- flower stems tend to twists around during development
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| Orchids grow from the Arctic to the Equator and south in all the continents except Antarctica. The orchids of greatest horticultural interest to date are the tropical epiphytes. The family of Orchids contains more species than any other family of plants (some botanists estimate the family to contain some 20,000 to 25,000 species). It is believed that many undiscovered or undescribed orchids exist (especially in the South American rainforest). These orchids may be lost forever if destruction of these rainforests continues unabated. Orchids typically come in two main forms; Monopodial orchids and Sympodial orchids. Monopodial orchids have stems that grow indefinitely. In this type of orchid, leaves always grow from the end of a stem. Monopodial orchids often produce aerial roots along their stems. The flower spikes (or inflorescence) in monopodial orchids grow from the side of the stem (not from the end). Popular cultivated monopodial orchids include the Vandas and the Spider or Scorpion orchids (Aracnis and related genera) Sympodial orchids are characterized by having a succession of shoots or bulb like stems, referred to as pseudobulbs, each arising from the base of the one before it. Each pseudobulb has limited growth. Roots tend to form at the base of pseudobulbs, or along the rhizome (occasionally however, young plants complete with roots may form high up on the parent stem). The flower spike of sympodial orchids arise from the base of the pseudobulb, the end of the pseudobulb, some point along it, or even from a rhizome. The majority of tropical orchids are sympodial. Popular cultivated sympodial orchids include the Cattleyas, Dendrobiums, Oncidiums and Spathoglottis species. | 
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| | Monopodial Orchids | Sympodial Orchids | Orchids are also described according to their manner of growth; whether terrestrial, epiphytic, climbing or lithophytic. Terrestrial orchids, as their name would suggest grow and flower on the ground. Spathoglottis orchids are terrestrial. Epiphytic orchids are found naturally in the canopy of trees. These are the main group of tropical orchids. As they are epiphytes, they use the trees for support and exposure to sunlight, but do not directly take any nourishment from the trees on which they grow. They produce aerial roots which do not thrive in soil. Many Vandas are epiphytic. Climbing orchids are monopodial. They often originate on the ground and climb up trees. These orchids are characterized by extensive aerial roots. Lithophytic orchids grow on rocks. This type of orchid is rare and not commonly cultivated. Bulbophyllum membranaceum is an example of a lithophytic orchid. Copyright © 2003 Stephen Proverbs ( c/o University of the West Indies, Cave Hill Campus). All rights reserved.
Revised: December 15, 2003 | 
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