The Orchids (Orchidaceae) are among the most diverse plant families. They get their name from the Greek orchis, testicle, from the appearance of the pseudobulbs in some terrestrial species. Roughly 30,000 species have been described, and at least 60,000 more hybrids have been produced by horticulturalists. They are monocotyledons, with flowers composed of 3 sepals and 3 petals (one of which is usually enlarged and called the "lip"). The reproductive organs in the centre have been transformed into a structure called the column. Ranging in size from tiny moss-like Pleurothallis species to massive Gramatophyllums (20 feet+) in New Guinea, their beauty and sophistication have captivated many. See genera list at bottom of page.
Most orchids are epiphytic, residing on tree limbs without parasitizing resources as, e.g., mistletoes do. Others live on the ground, often in shaded places. Almost all the species rely heavily upon mycorrhizal associations with various fungi that decompose surrounding matter, freeing up water-soluble nutrients. Most orchid seeds are extremely tiny, with no food reserves (endosperm), and will not germinate without such a symbiont to supply nutrients in the wild. Techniques have now been devised for germinating seeds on a nutrient-containing gel, eliminating the requirement of the fungus for germination, and greatly aiding the propagation of rare and endangered species.
It is in their reproductive methods that orchids truly shine. The Paphiopedilums (Lady Slippers) have a deep pocket that traps visitors, with just one exit. Passage through this exit leads to pollinia being deposited on the insect. A Eurasian genus has flowers that look so much like female bumble bees that males flying nearby are irresistibly drawn in. An underground orchid in Australia never sees the light of day, but manages to dupe ants into pollinating it. The Masdevallia stinks like a rotting carcass, and the forest flies it attracts assist its reproduction. A species discussed briefly by Darwin actually launches its viscid pollen sacs with explosive force. Some Phalaenopsis species in Malaysia use subtle weather cues to coordinate mass flowering.
There are a great number of tropical and subtropical orchids, and these are the most commonly known, as they are available at nurseries and through orchid clubs across the world. There are also quite a few orchids which grow in colder climates, although these are less often seen on the market.
- Ophrys apifera, bee orchid
- Gymnadenia conopsea, fragrant orchid
- Anacamptis pyramidalis, pyramidal orchid
- Dactylorhiza fuchsii, common spotted orchid
The family of orchids is remarkably diverse. The plants found in "casual" culture, such as Phalaenopsis, Cattleya, Dendrobium, and so forth, represent a tiny fraction of the thousands of varieties of orchids. Also within the Orchidaceae are "leafless" orchids, which often appear as nothing more than masses of roots, achlorophyllous orchids that are entirely reliant upon their mycorrhizal symbiont for their nutrition, "jewel" orchids with foliage that is as pretty as their flowers, and so many others that are capable of affecting the most dedicated of growers very deeply.
A selection of Orchid genera follows:
Aerangis; Aerides; Anacamptis; Angraecum; Anguloa; Ascocenda; Barkeria; Bletilla; Brassavola; Brassia; Bulbophyllum; Catasetum; Cattleya; Cirrhopetalum; Coelogyne; Cymbidium; Cypripedium; Dactylorhiza; Dendrobium; Disa; Dracula; Encyclia; Epidendrum; Epipactis; Eria; Eulophia; Gongora; Goodyera; Gramatophyllum; Gymnadenia; Habenaria; Herschelia; Laelia; Lapanthes; Liparis; Lycaste; Masdevallia; Maxillaria; Mexipedium; Miltonia; Mormodes; Odontoglossum; Oncidium; Ophrys; Orchis; Paphiopedilum; Paraphalaenopsis; Peristeria; Phaius; Phalaenopsis; Pholidota; Phragmipedium; Platanthera; Pleione; Pleurothallis; Pterostylis; Renanthera; Restrepia; Rhynchostylis; Saccolabium; Sarcochilus; Satyrium; Selenipedium; Serapias; Sophronitis; Spiranthes; Stanhopea; Stelis; Trias; Trichocentrum; Trichoglottis; Vanda; Vanilla; Zeuxine; Zygopetalum.
For a great read about the insane world of the orchid lover, try Eric Hansen's Orchid Fever Methuen.