Phalaenopsis/ˌfælɨˈnɒpsɪs/Blume (1825), known as the Moth Orchid, abbreviated Phal in the horticultural trade, is an orchidgenus of approximately 60 species. Phalaenopsis is one of the most popular orchids in the trade, through the development of many artificial hybrids.
The generic name means "Phalaen[a]-like" and is probably a reference to the genus Phalaena, the name given by Carl 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.
Most are epiphytic shade plants; a few are lithophytes. In the wild, some species grow below the canopies of moist and humid lowland forests, protected against direct sunlight; others grow in seasonally dry or cool environments. The species have adapted individually to these three habitats.
Possessing neither pseudobulbs nor rhizome, Phalaenopsis shows a monopodial growth habit: a single growing stem produces one or two alternate, thick, fleshy, elliptical leaves a year from the top while the older, basal leaves drop off at the same rate. If very healthy, a Phalaenopsis plant can have up to ten or more leaves. The inflorescence, either a raceme or panicle, appears from the stem between the leaves. They bloom in their full glory for several weeks. If kept in the home, the flowers may last two to three months.
Some Phalaenopsis species in Malaysia are known to use subtle weather cues to coordinate mass flowering.
The genus can be classified into two groups :
A group of species with a long, branched inflorescence (up to 1 m long) and large, almost round flowers with rose or white tints.
A group of species with short stems and less rounded, waxy flowers with more pronounced colors.
Based on DNA evidence, the genera Doritis Lindl. and Kingidium P.F.Hunt are now included in Phalaenopsis, according to the World Checklist of Selected Plant Families. However not every specialist in this field accepts these taxonomic changes.
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. Many are hybrids of Phalaenopsis amabilis, Phalaenopsis schilleriana or Phalaenopsis stuartiana.
Post-pollination changes in Phalaenopsis orchids
Phalaenopsis are 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, thus escaping programmed cell death. In producing chloroplasts, they turn green, become fleshy and apparently start to photosynthesize, as leaves do.
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 tetraploid 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 commercial production has become an industry.
In nature, Phalaenopsis species are typically fond of warm temperatures around 20 to 35 °C (68-95 °F), but are adaptable to conditions more comfortable for human habitation in temperate zones (15 to 30 °C or 59 to 86 °F); at temperatures below 18 °C (64.4 °F) overwatering causes root rot. Phalaenopsis requires high humidity (60-70%) and low light of 12,000 to 20,000 lux. However, Phalaenopsis orchids can adapt to the lower humidity found in most homes. They are also typically hardier than other species of orchids, and this makes them particularly popular among first-time orchid growers.
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 basal leaf tissue. Over about three months the spike elongates until it begins to swell fat buds which will bloom.
It was previously believed that flowering is triggered by a night-time drop in temperature of around 5 to 6 degrees over two to four consecutive weeks, usually in the fall, and a day-time drop in temperature to below 29 °C (84 °F). 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 (81 °F), with a definite inhibition of flowering at temperatures exceeding 29 °C (84 °F). The long-held belief that reduced evening temperatures control flower initiation in Phalaenopsis is shown to be false. Rather, lower daytime temperatures influence flowering, while night time temperatures do not appear to have any effect.
^Mohammad Babar Ali, Serida Khatun, Eun-Joo Hahn and Kee-Yoeup Paek,, 2006. "Enhancement of phenylpropanoid enzymes and lignin in Phalaenopsis orchid and their influence on plant acclimatisation at different levels of photosynthetic photon flux". Plant Growth Regulation volume 49, Numbers 2-3, pages 137-146, doi:10.1007/s10725-006-9003-z