Plant Common Name
Intrigue, murder and thievery have followed the orchid; world explorations have been launched and fortunes won all in the pursuit of these exotic flowers. Since the 19th century, when tropical orchids were first introduced to Europe, orchids have inspired human desire and greed because of their rarity, collectability and indescribable beauty.
Measured in geologic time Orchidaceae was once thought to be a newer family but recent research has shown it is much older. One of the largest plant families, there are more than ~880 genera, ~25,000 species and hundreds of thousands of cultivars, varieties and hybrids. Orchids are found growing all over planet Earth with the exception of ice-covered mainland Antarctica, deep dry deserts and open water. Most are epiphytes (tree dwellers), while others are lithophytes (rock dwellers). Many temperate orchids are terrestrial, meaning they grow in soil like most other plants. One species is an annual, while all others are perennial. There are even a few parasitic subterranean orchids that grow completely underground. The highest numbers of orchid species are found in sub-tropical and tropical regions.
Orchid plants and flowers are extremely variable but share common characteristics that mark them as orchids. All are monocots; which means they are related to plants like lilies and grasses. The leaves tend to be linear or oblong, with parallel leaf veins and flower parts in threes. The flowers usually have two rows of three showy petal/tepals. One or more of the petals may be lip-like and designed to attract or guide insects into the flowers for pollination. In the flower, male and female reproductive parts are fused into a single structure called the column, which holds the pollen that is usually bound together into two large masses, called pollinia, which only orchids have. Some orchids have a pleasant fragrance, others stink like rotten meat and some have no scent at all. The microscopic seeds are produced in fleshy green pods that age to brown. Sometimes there are more than a million seeds per pod.
One odd fact is that most orchid flowers twist upside down as they age. When they first open their floral lips, or pollinator landing pads, are on the upperside of the flower and as they are the lip rotates to the lowerside of the flower. The lip may twist clockwise or counterclockwise. Most rotate by 180° but a few twist to 360°. It is believed that this facilitates the timing of pollination and serves as a cue to prospective pollinators.
There are two common forms of epiphytic orchid plants, monopodial and sympodial. Monopodial plants lack bulbous bases (pseudobulbs), continually grow from the tip of the central growing point, and send out thick aerial roots along the stems. The popular Vanda is a monopodial orchid. Sympodial orchids commonly have bulbous water-storing bases called pseudobulbs and creep laterally along growing surfaces with thick roots that appear at the base of the bulbs. The common florists Cattleya has a sympodial habit. The roots of all epiphytic species are often covered with a spongy surface called velamen, which aids in water and nutrient absorption and is protective.
The culture of orchids is as variable as locations where they are found growing naturally. Each species has its own needs for best growth and flowering. Many of the sub-tropical and tropical epiphytes, such as Cattleya, Oncidium and Phalaenopsis, prefer bright but filtered light with high humidity and regular water. Cool season or mountainous species, like Masdevallia, Lycaste and Miltonia, require bright light and cool nights. Epiphytes grow best in special mixes of bark and tree fern while terrestrials need rich potting soil.
Orchids are thought to be difficult to grow, but many are quite easy and will grow will in a bright window (no full sun) on a tray of rocks, to increase drainage and humidity, and require regular water and fertilizer when in active growth.