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Phalaenopsis |
| Phalaenopsis | ||||||||||||||||||||
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 Closeup of a Phalaenopsis flower
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| Phalaenopsis amabilis Blume, (1825) |
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see text. |
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Phalaenopsis (Blume 1825) is a genus of approximately 60 species of orchids (family Orchidaceae). The abbreviation in the horticultural trade is Phal. Phalaenopsis is one of the most popular orchids in the trade, through the development of many artificial hybrids.
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The generic name means "Phalaen[a]-like" and is probably a reference to the genus Phalaena, the name given by Carolus Linnaeus to a group of large moths; the flowers of some species supposedly resemble moths in flight. For this reason, the species are sometimes called Moth orchids.
They are native throughout southeast Asia from the Himalayan mountains to the islands of Polillo and Palawan of the Philippines and northern Australia. Orchid Island off Taiwan is named after this orchid. Little is known about their habitat and their ecology in nature since little field research has been done in the last decades.
Most are epiphytic shade plants; a few are lithophytes. In the wild they are typically found below the canopies of moist and humid lowland forests, protected against direct sunlight, but equally in seasonally dry or cool environments. The species have adapted individually to these three habitats.
Phalaenopsis shows a monopodial growth habit. An erect growing rhizome produces from the top one or two alternate, thick and fleshy, elliptical leaves a year. The older, basal leaves drop off at the same rate. The plant retains in this way four to five leaves. If very healthy, they can have up to ten or more leaves. They have no pseudobulbs. The raceme appears from the stem between the leaves. They bloom in their full glory for several weeks. If kept in the home, they usually last two to three months.
Some Phalaenopsis species in Malaysia are known to use subtle weather cues to coordinate mass flowering.
The species can be classified into two groups :
In terms of particular lifeform terminology, one can also characterize these plants as hemicryptophyte or chamerophyte :
The genera Doritis Lindl. and Kingidium P.F.Hunt are now included in Phalaneopsis, based on DNA-evidence (according to the World Checklist of Monocotyledons, Royal Botanical Gardens, Kew) (See also ref 1). However this is not implicitly accepted by every specialist in this field.
Intensive cross-fertilization has produced a great number of hybrids in all colors and variations. These are usually more adaptable to artificial conditions than their botanical ancestors. Most are hybrids of Phalaenopsis amabilis with Phalaenopsis schilleriana or Phalaenopsis stuartiana.
There is no true intergeneric hybrid between Phalaenopsis and the closely related Paraphalaenopsis. However, according to the RHS, there is a grex (i.e. all orchids derived from crossing the same two or more parent species; the name also covers all offspring from that particular cross). Phalphalaenopsis Doris Thornton is currently the one and only registered (1977) grex that represents a cross between a Paraphalaenopsis (x thorntonii) and a Phalaenopsis (Doris). Therefore, strictly speaking, the genetic barrier between these two closely related genera has not been crossed. But, since there are only very few true Phalaenopsis species in cultivation (most are hybrids), the possibility of a true intergeneric hybrid is not to be excluded.
Phalaenopsis are not only outstanding in their beauty, but also unique in that in some species, the flowers turn into green leaves after pollination. As in many other plants, the petals of the orchid flowers serve to attract pollinating insects and protect essential organs. Following pollination, petals will usually undergo senescence (i.e. wilt and disintegrate) because it is metabolically expensive to maintain them. In many Phalaenopsis species such as P.violacea, the petals and sepals find new uses following pollination and thus escaping programmed cell death. By inducing the formation of chloroplasts, they turn green, become fleshy and apparently start to photosynthesize, just like leaves. 1
Phalaenopsis are among the most popular orchids sold as potted plants owing to the ease of propagation and flowering under artificial conditions. They were among the first tropical orchids in Victorian collections. Since the advent of the tetrapoloid hybrid Phalaenopsis Doris, they have become extremely easy to grow and flower in the home, as long as some care is taken to provide them with conditions that approximate their native habitats. Their production has become a commercial industry.
In nature, they are typically fond of warm temperatures (20 to 35 °C), but are adaptable to conditions more comfortable for human habitation in temperate zones (15 to 30 °C); at temperatures below 18 °C watering should be reduced to avoid the risk of root rot. Phalaenopsis requires high humidity (60-70%) and low light of 12,000 to 20,000 lux. Flowering is triggered by a night-time drop in temperature of around 5 to 6 degrees over 2 to 4 consecutive weeks, usually in the fall, and a day-time drop in temperature to below 29 °C2.
Phalaenopsis prefer to be potted in osmunda fiber (tree fern roots), a nearly ideal medium, but this has become expensive. More usual now is fir bark, which is more free-draining than sphagnum moss. Keep them in pots with a lot of drainage. One of the common blunders that new growers make is to rot the roots. Overwatering and poor drainage cause the roots to deteriorate, therefore killing the plant. The safest thing to do is to water when you feel the potting medium and find it is dry through and through.
Light is vital to the well-being of the Phalaenopsis orchid. Keep it in indirect light near a southern window. Be sure the sun does not directly reach the leaves, which will cause burning and unaesthetic brown marks. If the leaf feels hot to the touch, move it away immediately! On the other hand, phalaenopsis grown in poor dark areas tend to grow floppy dark green leaves and rarely flower.
Phalaenopsis roots are quite thick, and the green point at the ends signifies that the root is actively growing. It is okay for them to climb out of the pots. Keep the plant fertilized with a 1/4 diluted strength balanced fertilizer three times out of four waterings.
The flower spikes appear from the pockets near the base of each leaf. The first sign is a light green "mitten-like" object that protrudes from the leaf tissue. In about three months, the spike elongates until it begins to swell fat buds. The buds will thus bloom. Usually you can tell what color the Phalaenopsis is by looking at the bud color. After the flowers fade, some people prefer to cut the spike above the highest node (section). This may produce another flower spike or more rarely a keiki (a baby orchid plant that can be planted).
Using two Phalaenopsis clones, Matthew G. Blanchard and Erik S. Runkle (2006) established that, other culture conditions being optimal, flower initiation is controlled by daytime temperatures declining below 27°C, with a definite inhibition of flowering at temperatures exceeding 29°C. The long-held traditional belief that reduced evening temperatures control flower initiation in Phalaenopsis appears to be false. 2
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