Phalaenopsis or moth orchids are currently the most popular orchids. Photo: chipandchristianna.com
So many of us grow orchids, but what do we really know about them? Here are some fun facts about this fascinating group of plants.
- The orchid family (Orchidaceae) is, with the Asteraceae* or sunflower family, the largest in the world, containing some 28,000 species distributed in 763 genera. There are four times more orchid species on this planet than mammal species!
*Which family is actually larger is debatable, because data on different species is always changing.
- Orchids are both very ancient and very modern. They are among the oldest known flowering plants, with the oldest dating back 112 million years ago to the Early Cretaceous, when dinosaurs ruled the earth. By 64 million years ago, they had evolved pollinia and by 35 million years ago, many had become epiphytes. However, orchids continue to evolve to this day and about 20 new species are described every year.
- Orchids are not just tropical, as you might expect, given the current popularity of houseplant orchids, but are found all over the world, from the equator to the Arctic Circle. And in most environments, too, from arid climates to tropical jungles. They are found on every continent except Antarctica.
- Orchid flowers have variable durations. Some last only hours (Sobralia spp, for example, last barely a day) while others last months (many Phalaenopsis hybrids). Probably the average lifespan of an orchid flower is about 2 to 4 weeks.
- The world’s largest orchid, is the giant orchid or tiger orchid, Grammatophyllum speciosum, which can measure up to 7.62 m (25 ft) in height and weigh up to 2 tons, bearing thousands of abundantly spotted flowers at once. In spite of its size, it mostly grows as an epiphyte, high up in the branches of forest trees on the islands of Southeast Asia.
- The world’s smallest orchid is, officially, Platystele jungermannioides of the cloud forests of Mexico, Guatemala, Costa Rica and Panama. The plant itself about the size of a dime, including the leaves, roots and flowers. An even smaller orchid was recently discovered in Ecuador, but it has yet to be officially described.
- Orchids have the smallest seeds in the world, no larger than a speck of dust, with those of the New Caledonian species Anoectochilus imitans are said to be the smallest of all, measuring just 0.05 mm in length. A single seed capsule of some species can contain up to 4 million seeds. This is largely because orchid seeds, unlike other seeds, have no food reserve. To germinate, most first have to form in a mycorrhizal relationship with a fungus that will supply the nutrients they need in order to grow.
- Only one orchid among all the thousands of species is considered to have an edible fruit. The seed pods (beans) of vanilla orchids (Vanilla spp.) are harvested and produce the well-known vanilla flavoring. It is the second most expensive spice in the world after saffron.
- Moth orchids (Phalaneopsis species and hybrids) are currently the most widely grown houseplants in the world, now superceding the popular Christmas plant, the poinsettia (Euphorbia pulcherrima), with sales increasing annually. They are grown by the millions on all continents and, yes, even—indoors, of course—in Antarctica, where there are reports of one being grown in a research studio.
- The name orchid comes from plants in the the genus Orchis, such as Orchis mascula, and derives from the Ancient Greek word orchis meaning “testicle”; because of the shape of the paired underground tubers of this terrestrial European species. The term “orchid”, which is just a shortened form of the family Orchidaceae, was not introduced until 1845.
- Orchid flowers are quite unusual. While they have the usual 6 tepals (3 petals and 3 sepals) common to most other monocots, one of the petals is highly modified. Called the labellum (or lip), it is typically quite different from the other tepals both in shape and color. It usually functions to attract insect pollinators and direct them to the flower’s column where it’s sexual organs are concentrated.
- The column in the center of the flower is fairly unique as well. It’s a fusion of the stamen, where the pollen is made, and stigma, where the pollen germinates. On most other flowers, these are separate parts, rather grouped into a single organ.
- The pollen of orchids is not exposed on the anther at the tip of stamen as in most flowers, but is condensed into a dense mass called a pollinium (plural pollinia). When an insect visits an orchid flower, the pollinia is typically glued to its body and the insect then carries it to the flower of another orchid of the same species where it becomes caught and is pulled free, thus fecundating the flower and leading to seed production.
- Orchid roots too can be pretty special, especially in the case of epiphytic orchids (the ones that grow on trees). They’re aerial and reach out in all directions, eventually fixing themselves to branches and bark in the wild. They’re very thick and covered with a spongy whitish to brownish epidermis called velamen whose role is to absorb and hold moisture. When moistened, these roots often show an underlying greenish coloration due to the presence of chlorophyll and carry out some photosynthesis. Indeed, some orchids have no leaves at all and carry out photosynthesis uniquely through their photosynthetic roots.
- Orchids are classified into two groups. Those that grow up from a single stem, such as Phalaneopsis and Vanda orchids, are said to be monopodial (mono = single / pod = foot). The majority, however, grow horizontally along a creeping, branching rhizome and are called sympodial (sym = many / pod = feet). This includes such genera as Cattleya, Cympdidium, Dendrobium and Oncidium. Many tropical sympodial orchids produce a line of bulblike structures at their base called pseudobulbs. Each pseudobulb blooms only once, but by then another or several other pseudobulbs will be forming and each will bloom in its turn. Leafless older pseudobulbs that have already bloomed are called back bulbs and serve as an energy and water reservoir for newer growth. Monopodial orchids are usually reproduced by stem cuttings, unless they produce an offset (keiki or baby orchid) that can be cut free and rooted. Sympodial orchids are mostly multiplied by division.
So there you go: orchids have been mass-produced to the extent they are now common, everyday houseplants … but that doesn’t mean they don’t have their fun little secrets!