Phalaenopsis (), also known as moth orchids,
Description
Orchids in the genus
Phalaenopsis are monopodial epiphytic, sometimes lithophytic
Herbaceous plant with long, coarse roots with
(which allow for gaseous exchange of the
photosynthetic roots),
[李嘉慧, & 李哖. (1991). 台灣蝴蝶蘭根和葉的形態與解剖的特性. 中國園藝, 37(4), 237–248.] 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
or
. The
and
are free from and spread widely apart from each other. The sepals are usually larger than the 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.
Reproduction
Unlike most other angiosperms, the development of the
is triggered by
pollination. Therefore a temporal mismatch of male and female
exists (i.e. the male structures are ready but the female structures have not yet been fully developed). In orchids,
fertilisation occurs within days or months after the pollination event. After pollination occurs, the stigmatic cavity is often closed through swelling of the column. As a result, the
Pollinium are completely enclosed. The pollen germinates after enclosure and tubes are produced. In
Phalaenopsis aphrodite, pollen tubes entered the ovary within 3 days after pollination. Within 15 days, pollen tubes evenly spread throughout the
Placentation cavities. Within 60 days after the pollination event, 30.6% of the tips of the pollen tubes started to enter the micropyles (i.e. entry points) of the ovules. Finally, 65 to 70 days after the pollination event, fertilisation occurred.
Phalaenopsis are unique in that in some species of the subgenus Polychilos, 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 , they turn green, become fleshy, and start to photosynthesize, as leaves do.
Phytochemistry
Floral fragrance has been analysed for several species. The fragrance of
Phalaenopsis bellina has been shown to be composed of about 79 compounds, primarily of the
terpenoid class. It was most intense in the morning.
In Phalaenopsis, phenylpropanoid enzymes are enhanced in the process of plant acclimatisation at different levels of photosynthetic photon flux.
Taxonomy
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 φαλαινα () meaning 'a kind of moth'
with the
-opsis meaning 'having the appearance of' or 'like'.
[ p. 140]
The genus name is abbreviated Phal. horticulturally.
Infrageneric structure
The large monophyletic genus
Phalaenopsis is divided into several sub-units. They are either regarded as subgenera or as sections. Not all of them are monophyletic.
The subgenus
Polychilos is monophyletic and it is divided into two subclades. The subgenus
Phalaenopsis is paraphyletic under its current definition. Likewise the evidence shows that the subgenera
Aphyllae and
Parishianae, as currently defined, are not monophyletic. The position of the monotypic subgenus
Proboscidioides, which only consists of
Phalaenopsis lowii, suggests a close relationship with the subgenus
Aphyllae.
The following phylogenetic tree is a simplified tree to show the general placement of the main infrageneric groups. It is meant to give an overview, despite the contended monophyly of some of the respective groups.[Tsai, C. C. (2003). Molecular phylogeny, biogeography, and evolutionary trends of the genus Phalaenopsis (Orchidaceae). PHD dissertation.]
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:
[ Kew World Checklist of Selected Plant Families][ Flora of China v 25 p 448, 羽唇兰属 yu chun lan shu, Ornithochilus (Wallich ex Lindley) Bentham & J. D. Hooker, Gen. Pl. 3: 478, 581. 1883.]
-
Ornithochilus cacharensis Barbhuiya, B.K.Dutta & Schuit. - Assam
-
Ornithochilus difformis (Wall. ex Lindl.) Schltr. - Guangdong, Guangxi, Sichuan, Yunnan, Assam, India, Bhutan, Nepal, Myanmar, Thailand, Vietnam, Laos, Borneo, Sumatra, Peninsular Malaysia
-
Ornithochilus yingjiangensis Z.H.Tsi - Yunnan
Hygrochilus
The former genera
Sedirea and
Hygrochilus were incorporated into
Phalaenopsis subgen.
Hygrochilus. The interspecific relationships within the subgenus
Hygrochilus are poorly understood and are a source of confusion. The type species of the subgenus is
Phalaenopsis hygrochila.
The species of this subgenus are morphologically distinct from the other subgenera, due to their four pollinia and spurred flowers, as well as their unusually long stems.
Species list
See List of
Phalaenopsis species
Intergeneric hybrids
See List of
Phalaenopsis species
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,
Phalaenopsis rosenstromii, Endemism to
Queensland, Australia.
has become naturalised in Costa Rica, Panama, and Suriname.
[Belfort-Oconitrillo, N., Salguero, G., Oses, L., Gil-Amaya, K., Rojas-Alvarado, G., Chinchilla, I. F., ... & Karremans, A. P. (2024). New species and records of Orchidaceae from Costa Rica. IV. Lankesteriana, 24(2), 141–192.]
Ecology
Pollination of
Phalaenopsis pulcherrima through bees, specifically
Amegilla nigritar, has been recorded in China.
This species employs a deceptive pollination strategy. The orchid does not provide rewards to pollinators. It benefits from blooming in the same period as rewarding species.
Amegilla is the most important pollinator, but diurnal insects – such as four species of bees, two species of butterflies, one species of moth and two other unidentified insects – have also been observed to interact with the flowers.
Conservation
Many species are highly threatened. For instance
Phalaenopsis lindenii is categorized as endangered,
is categorized as vulnerable
and
Phalaenopsis micholitzii is categorized as critically endangered.
Some species, like
P. javanica, are believed to be extinct in the wild.
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 era collections. Since the advent of the
Polyploidy 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 Celsius (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 and the plants will also drop their leaves if they experience temperatures below 60 °F for extended periods. Phalaenopsis prefer moderate 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.[ Growing Conditions for Phalaenopsis Orchids, Accessed 11/11/2012 ]
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.
Award of Garden Merit
In cultivation in the United Kingdom, the following have been awarded the Royal Horticultural Society's Award of Garden Merit:
-
Brother Pico Sweetheart gx.
-
Phalaenopsis amabilis
-
Yellow Lightning gx.
-
Olaf Gruss & Manfred Wolf - Phalaenopsis; Edition Ulmer, (in German)
-
Eric A. Christenson - Phalaenopsis: a Monograph;
-
Harper, Tom (February 2004). Phalaenopsis Culture: Advice for Growing 20 Species. Orchids Magazine 73 (2). Delray Beach, FL: American Orchid Society, 2004
-
Leroy-Terquem, Gerald and Jean Parisot. 1991. Orchids: Care and Cultivation. London: Cassel Publishers Ltd.
-
Schoser, Gustav. 1993. Orchid Growing Basics. New York: Sterling Publishing Co., Inc.
-
White, Judy. 1996. Taylor’s Guide to Orchids. Frances Tenenbaum, Series Editor. New York: Houghton-Mifflin,
External links
