Phalaenopsis

Phalaenopsis , commonly known as moth orchids, is a genus of about seventy species of plants in the family Orchidaceae. Orchids in this genus are monopodial epiphytes or lithophytes with long, coarse roots, short, leafy stems and long-lasting, flat flowers arranged in a flowering stem that often branches near the end. Orchids in this genus are native to India, Taiwan, China, Southeast Asia, New Guinea and Australia with the majority in Indonesia and the Philippines.
Description.
Orchids in the genus "Phalaenopsis" are monopodial epiphytic, sometimes lithophytic herbs with long, coarse roots and short leafy stems hidden by overlapping leaf bases. The leaves are usually arranged in two rows, relatively large and leathery, oblong to elliptic and sometimes succulent. A few to many, small to large, long-lasting, flat, often fragrant flowers are arranged on erect to hanging racemes or panicles. The sepals and petals are free from and spread widely apart from each other. The lateral sepals are usually larger than the dorsal sepal and the petals much wider than the sepals. The labellum is joined stiffly to the column and has three lobes. The side lobes are erect and more or less parallel to each other and the middle lobe sometimes has a pair of appendages or antennae.
Taxonomy and naming.
The genus "Phalaenopsis" was first formally described in 1825 by Carl Ludwig Blume and the description was published in "Bijdragen tot de flora van Nederlandsch Indië". The name "Phalaenopsis" is derived from the Ancient Greek word "phalaina" (φαλαινα) meaning "a kind of moth" with the suffix "-opsis" meaning "having the appearance of" or "like".
The genus name is abbreviated "Phal." horticulturally.
"Ornithochilus".
The former genus "Ornithochilus" was merged with "Phalaenopsis" and is considered by some to be a subgenus. Its members have distinctly 4-lobed, fringed labella with a short, curved spur situated near the middle of the lip as opposed to the base. "Ornithochilus" formerly had three known species, native to China, the Himalayas and Southeast Asia:
Distribution.
Species of "Phalaenopsis" are found from India to southern China, Indochina, Malaysia and from Indonesia to the Philippines and New Guinea. There is a single species endemic to Queensland. The greatest disversity of phalaenopsis occurs in Indonesia and the Philippines.
Species.
The following is a list of "Phalaenopsis" species accepted by the World Checklist of Selected Plant Families as at January 2019:
Intergeneric hybrids.
The following nothogenera have been established for intergeneric hybrids which include species of "Phalaenopsis" as ancestors.
Post-pollination changes.
"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 usually will undergo senescence (i.e. wilt and disintegrate) because it is metabolically expensive to maintain them. However, 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 start to photosynthesize, as leaves do.
Ecology.
In "Phalaenopsis", phenylpropanoid enzymes are enhanced in the process of plant acclimatisation at different levels of photosynthetic photon flux.
Use in horticulture.
"Phalaenopsis", abbreviated Phal in the horticultural trade, 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.
If very healthy, a "Phalaenopsis" plant may have up to ten or more leaves. They bloom in their full glory for several weeks. If kept in the home, the flowers may last two to three months after which a phalaenopsis orchid will need to conserve energy for further leaf, bud, and root development.
In nature, "Phalaenopsis" species are typically fond of warm temperatures, thriving in 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 59–86 °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 approximately three months the spike elongates until it begins to swell fat buds that will bloom.
It previously was 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 . 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 , with a definite inhibition of flowering at temperatures exceeding . The long-held belief that reduced evening temperatures control flower initiation in "Phalaenopsis" was shown to be false. Rather, lower daytime temperatures influence flowering, while night time temperatures do not appear to have any effect.
The effect of fertilizer source and medium composition on vegetative growth and mineral nutrition has been studied.
AGM.
In cultivation in the UK, the following have been awarded the Royal Horticultural Society's Award of Garden Merit: