Contents
Flowers  
Flowering Season
Callus  
Perianth
Insect-Pollinatated Flowers
Fragrance
Leaf  Root 
Inflorescence
Regional Differences (Flower)
Regional Differences (Leaf)
Similar Species

Flowers

 The genus Phalaenopsis comprises over 60 native species according to the latest classification. The flower is composed of perianth lobes, a lip and a column. The perianth lobes are further divided into petals and the dorsal and lateral sepals, and the lip is segmented into a midlobe, lateral lobe, cirrus, and callus, as shown in Fig. 1. A large majority of the species have a star-shaped perianth that diverges into various textures with colors ranging from blue to red. This site posts 58 native Phalaenopsis species on the Gallery page.

 The time of blooming, and the number and longevity of flowers are distinct for every species. P. cornu-cervi opens a few flowers at a time but has a very long blooming period (more than six months). In contrast, P. amabilis and P. schilleriana open many flowers at a time but for a short period. The floral season, depending on the habitat, is considered to keep a mutualism with pollinators. Figure 1 illustrates the nominal designation of flower segments.

  Due to the diverse distributions in the monsoon and tropical rainforests of Southeast Asia, the floral seasons of Phalaenopsis vary. Although a few species bloom twice a year or at irregular times (e.g. P. amboinensis), the majority of species have a single flowering time per year in response to the change of seasons.

 In a horticultural environment with artificially controlled temperature, watering and moisture, the flowering period may differ more or less from the morphology in nature.

 Mutant varieties in Phalaenopsis species, e.g., alba, aurea, and coerulea, have been found, as with other orchid genera. Such mutant floras rarely exist in nature, probably fewer than 1/10,000 cases. Most of the varieties in the current marketplace have been reproduced by tissue culture or mericlone propagation. It is said that some species, e.g., P. javanica and P. thalebanii, in the market are the seedlings of ex situ propagation and can no longer be found in their place of origin.


Fig. 1. Phalaenopsis Flower (Left: P.amabilis, Right: P. lueddemanniana f. mindanao)
  Figure 2 shows close up pictures around the lip of the perianth. The lips of Phalaenopsis are three bilaterally symmetric lobes with multitudinous shapes consisting of a midlobe, lateral lobes, and callus. The midlobe has further various shapes of lobules at the apical portion. Those are classified as follows:

1. long tendril at apex (e.g. amabilis)
2. crescent arch at apex (e.g. pantherina)
3. trichomes on surface (e.g. lueddemanniana
4. velvety texture on surface without trichomes (e.g. bellina
5. swing structured midlobe (e.g. lobbii
6. spoon-shaped surface (e.g. kunstleri

 Various forms of the midlobe might have evolved to entice specific pollinators (mainly bees) and allow them to hold on easily.


Fig. 2. Lip Structures

  Most species have lateral lobes tinged with yellow (nectar guide) and splotched with red inside for attracting pollinators. The sepals and petals of most Phalaenopsis have waxy, thick, and glossy epidermides. This feature apparently differs from the genus Cattleya, which mostly has thin and touchably-soft epidermides. The Phalaenopsisi species found in garden shops with showy colors and big flowers in alternate, distichous formations and long inflorescences are all hybrids that have been produced with complex crossbred or mericlone propagation from the parent species of mostly P. amabilis, P. aphrodite, P. schilleriana or P. amboinensis.


Flowering Seasons

 Table 1 lists the flowering seasons of native Phalaenopsis species. Many species overlap the seasons. The classifications in Table1 are referred to based on the horticulture environments in Japan, so they might be somewhat different from the native habitats.

Table1 Flowering Season of Phalaenopsis Species (season when blooming starts)
Seasons
Species
Remarks
March - May
amabilis, amboinensis, aphrodite, braceana, celebensis, cochlearis, doweryensis, floresensis, fuscata, gibossa, gigantea,
hainanensis, honghenensis, inscriptiosinensis, lamelligera, lobbii, lueddemanniana, mannii, micholitzii, minus, modesta, pallens,
parishii, philippinense, pulchra, schilleriana, stuartiana, sumatrana, tetraspis, venosa, wilsonii, zebrina

daytime: 25-30C
night-time: 18-20C

June - Sept.
bastianii, bellina, borneensis, chibae, corningiana, fasciata, fimbriata, inscriptiosinensis, javanica, kunstleri, lamelligera, lindenii, mariae,
pallens, sanderiana, violacea

daytime: 28 - 32C
night-time: 20-25C

Sept - Nov.
gigantea, hieroglyphica, lowii, maculata,
daytime: 25-30C
night-time: 18-20C
Dec. - Feb.
amabilis, aphrodite, schilleriana, stuartiana, viridis
daytime: 20-25C
night-time: 18-20C
All year around
appendiculata, cornu-cervi, equestris, pantherina

 Two characteristics are observed for the flowering morphology in native species. One is for many floweres to burst into bloomat at the same time but over a short period: 1 -2 months (see the species in Phalaenopsis section), and the other is for a few flowers to bloom at a time but for a long duration: 6 months or more (e.g. P. cornu-cervi, P. equestris). When flowering occurs soon after repotting, or in conditions of root rot or a homeostatic lack of nourishment, the flowering period will be extremely short and will finally fade within one week or so. A young plant or a plant with a few leaves will rarely grow big or develop many flowers. This is a form of self-protection to conserve strength and energy, which is not the original nature.


Callus

  A callus is the protuberance (calli) at the base of the lip-midlobe and between lateral lobes, as shown in Fig. 3 (the lips in the pictures are shown with the lateral lobes removed to make it easy to see the callus). There are three kinds of callus: one calli (uniseriate) at left, two sets of calli (biseriate), at center, and three sets of calli (triseriate), at right. The biseriate callus is divided into the anterior and posterior callus, and the anterior callus has a toothed or long bifurcated filiform, while the posterior callus is bifid or glandular. The central callus of triseriate is a bifid plate, as shown in the figure. (right).

The shape and structure of the callus as well as the lip form are very important to identify and classify the species.


Fig.3. Callus (left to right:amabilis, modesta, lamelligera) on lip (lateral lobes has been removed)

Column, Pollinia, and Capsule

 Figure 4 shows the column, stigmatic cavity, anther cap, and pollinia. The stigmatic cavity corresponds to the pistil. The column is straight or slightly curved, subcylindric, and dilated toward the apex. Picture (1) shows the stigma observed from below. It comprises the anther cap with a rostellum (ribbon-like band) covering the pollinia (yellow object seen through the cap). When the pollinator - a bee or wasp - visits the flower and touches the rostellum, the cap is easily removed when part of the band sticks to the pollinator's body or head. The pollinarium in pic. (4) consists of the pollinia, stipe, and viscidium. The viscidium has a strong adhesive and is hard to draw apart from the adherend once attached. Picture (2) shows the stigma after removing the anther cap; pic. 3 shows the anther cap and pollinia with a (tape-like) stipe. One edge of the stipe is stuck to the pollinia, and the other has a viscidium to stick to the pollinator. The stigma shown in pic. (2) has a talon that captures the pollinia in the cavity. This structure to separate the anther from the stigma also prevents self-pollination. When the pollinator with the stipe and the pollinia passes under the column, the pollinia is hooked into the cavity.The stigmatic cavity has no adherence, but the talon has the sticky substance at the base. Once the pollinia is hooked by the talon, a "pushmi-pullyu" action occurs between the pollinator and the talon. The viscidium on the stipe is stretched two - three times longer than the length of the stipe. The adhesion between the stipe and the pollinia is weaker than between the pollinator and the stipe. Finally, only the pollinia, or sometimes the stipe as well, remains in the cavity, slipping from the pollinator's body.

 The morphology of the pollinarium is a natural miracle, especially in how the pollinia bonds to the stipe like an adhesive tape, as shown in pic (4). Picture (5) shows the stigmatic cavity in which the pollinia and stipe has been caught. After a few days, the cavity is closed, and the pollinia remains (6). The right close-up picture (P. amabilis) shows the bound part of the pollinia and stipe.

Fig. 4 Column, Stigma, and Pollinia

 
Fig. 5 Cross-section of Column 5 Days after Pollination
  After the stigma catches the pollinia, it starts to close the cavity and wrap around the pollinia within 4 to 5 days. At the same time, the perianth starts to wither (e.g., subgenus Phalaenopsis) or changes its color to green (e.g., subgenus polychilos). In vivo of the stigma, the pollinia (yellow object in Fig. 5) is pushed to the ovary side, and several days after pollination it starts to build up the ovules by the hormone discharged from the pollinia.

 The fertilization is carried out within 40 - 50 days, and the ovary starts developing. It takes about 4 months to produce a seed with germ. During this period, the plant needs to be kept in temperatures around 20 - 25C. If the sultry nights or higher temperatures than above persist for several weeks, the ovary might turn yellow and drop or produce a seed without germ. Some species, e.g., P. lindenii, P. micholitzii, and alba (in all species) are especially sensitive to temperature during fertilization.

 After fertilization, the ovary grows thicker (convex-rounded) and longer. It develops into a fruit over a period of 3-4 months. The fruit is referred to as capsules on this site. The capsules have pigmentation in green (section amboinenses), ginger (stauroglottis section), and mixed shades (P. equestris). It has six grooves (six-sulcate) with various textures, e.g., glossy (subgenus Phalaenopsis) and touchably-soft (e.g., P. cochlearis, P. gigantea) as shown in Fig. 6. P. amabilis has two types of pigmentation according to habitat: brown (Borneo) and green (Indonesia). There are two types of perianth in post-pollination: one that contains chlorophyll, and one that withers. In the Phalaenopsis section, e.g., P. amabilis and P. schilleriana have a withered perianth, and in the Amboinenses and Zebrinae section, e.g., P. amboinensis (as shown in the picture below) has a perianth that keeps its shape with chlorophyll. The morphology of the post-pollination perianth is important in order to identify the species.

 Although it is possible to gather and cast the seeds four months after pollination, the capsules turn yellow, and the hull is partially split if it remains untouched for 6 to 10 months. Once the pigment starts to turn yellow, the hull splits off within a week. The split part is always underneath. It is interesting how to recognize the upper and lower sides of capsules. Figure 6 shows pictures of typical capsules. The images in the pictures have not been adjusted to a scale corresponding to the real size. P. gigantea and P. parishii are the largest and smallest capsules, (3:1), respectively.

Fig. 6 Capsule Shapes and Colors

Insect-Pollinated Flowers 

 The floral morphology of the Phalaenopsis species is thought to have been specially adapted to the ecological conditions. For example, the perianth texture and lip structure differ among species, which might be the result of evolution for mutualism with specific insects - pollinators - relying on the delivery of pollen to the same families. The morphological timing, such as putting out a small number of flowers at one time but for a long blooming time, or putting out many flowers for a short period, might be synchronized with the eclosion of pollinators, which would insure the success of pollination.

 The pollinarium adheres well to anything when touched. This characteristic to stick to anything (including insects unrelated to pollination) might run the danger of decreasing the success of pollination. Thus, the special structure of the perianth and lip might have been developed to entice specific insects to a specific type of flower. The individual texture and structure of the perianth were not necessary unless it needed a targeted insect. To have a specified shape and color could boost the odds of inviting specific insects flying between the same types of plants. Considering size and shape of the lip and column structures, the pollinators could be confined almost exclusively to bees, wasps, flies or gnats but not butterflies, moths or ants.

 What is it about the Phalaenopsis species that the insect is attractted to? The floral scent, nectar, pollen, form, color or texture? It is said that one of the attractants of, e.g. the genus Cattleya and Laelia, is the fragrance or the nectar. However, the genus Phalaenopsis does not appear to offer any food or energy sources such as nectar or pollen. Furthermore, many Phalaenopsis species have only a slight fragrance, and some species have no-scent (insensitive to the human nose). Another possibility is that a mimesis is the reason for the attraction. It might be as extreme as looking like the perianth texture and lip shape of the subgenus Parishianae. But this is not a common feature in the genus Phalaenopsis. Considering this, it is hard to find a unique and common attractant of the genus Phalaenopsis.

 According to the logic of evolution, insect-pollinated flowers evolved as follows: they first appeared as vegetation having powder-formed pollen. Their pollination system that relied on the wind blowing the pollen around was inefficient for the few and small-sized species because most pollen simply got blown away. By and by, insects appeared that ate the pollen. Though it meant that some pollen was lost due to being eaten by the insects, the insects flew to and fro between flowers resulted in more efficient pollination than from the wind blowing. Thus, many types of vegetation have evolved from wind-pollinated to insect-pollinated flowers.

 Subsequently, vegetation emerged that attracted insects by giving a tiny amount of nectar (if there was too much, the pollinator would be " stuffed" and wouldn't move on to other flowers) or fragrance and conveyed the pollen to other flowers, wrapping the hard pollinia up with a detachable anther cap and sticking the pollinia on the pollinator's body. At the first stage, the perianth was an actinomorphic flower (radially symmetrical from the top view), but at the next stage, the zygomorphic flower emerged which, with its asymmetrical shape, could block insects looking for food from getting to the nector within except, that is, for specific insects. To attract the pollinators, the species which could not offer nectar were scented, while non-scented species provided nectar instead. But providing such attractants is exhausting, so ultimately, the species evolved that did not have nectar nor a scent, but which had an attractant pheromone or a sexually deceptive strategy based on a representation of color, texture or shape.

 Research addressing the pollinators for the genus Phalaenopsis is rarely found. In other orchids, e.g., Cypripedium, a unique fragrance corresponding to each species exists, and the shape and size of the flower are used to specify the pollinator (e.g. Bombus, Apis, Halictidae, Syrphidae, and Muscomorpha), whereas the genus Paphiopedilum has no unique fragrance, and the attractant has not known yet. In Central and South America, there is an orchid which has no nectar nor is mimetic. It invites a bee (euglossine bee) using the fragrance that attracts males only. This bee rakes the secretion (basic ingredient of fragrance) with its forefoot and stores it in the sponge-like bag on its hind legs. What's behind this behavior is a strategy to produce pheromones that will attract females by mixing the secretion with his sputum. This morphology shows that the orchid is the most evolved genus in the orchid kingdom, maybe the most evolved among all flora.

  The CAM orchid - Phalaenopsis - is one of the most advanced genera, but the inducible factor or attractant ingredient has not been clarified. However, we can presume that the attractants of Phalaenopsis have varied according to the environment - fragrance (many of the subgenera Amboinenses), mimesis (subgenus Parishianae), color (subgenus Phalaenopsis) and various complex compositions - in the evolutionary process.


Fragrance 

 The representatively scented species in Phalaenopsis are, e.g., P. violacea, P. lueddemanniana, P. modesta, P. floresensis,,and P. gigantea. It is believed that the majority of Phalaenopsis species are not scented. Some species remit a scent for a short period after the blooming or in a specific time zone, and many are fragrant in the daytime, especially in the morning on clear days. P. kunstleri is an exceptional species that is odoriferous at night. We can detect a scent in some species only when they put out masses of flowers (e.g. P. equestris) even though our noses may be insensitive to a few flowers. Furthermore, some species have both scented and non-scented characteristics, which depend on the habitat or variety (e.g. P. cornu-cervi, P. modesta, P. hieroglyphica). All in all, Phalaenopsis can be said to be one of the floral-scented genera.

 The scent is an important factor to identify the species and its habitat. Nowadays, it is very hard to find native species of P. violacea and P. bellina in the market. Their hybridization has been attempted actively to obtain showy flowers in colors such as dark red and blue. Thus, we can see colorful flowers of P. violacea and P. bellinat in shops, which never existed in nature. The point is that many commercially available species are hybrids of select species or crosses between different habitats and are sold with the same name as the native species.

 The floral scent might be a useful characteristic to identify the species as a native or a hybrid. P. violacea has a spicy aroma, while P. bellina has a hint of lemon. P. modesta on Borneo island has a perceivable fragrance but it does not in Sumatra. P. cornu-cervi has the opposite characteristics to P. modesta. P. sumatrana and P. zebrina are very similar but have different scents. These regional variations of morphology might be closely related with the symbiosis between pollinators.

Table 2. Scents
scent
Species
strong
amboinensis, bellina, braceana, corningiana, fimbrata, floresensis, gigantea, hieroglyphica, hainanensis, honghenensis,
inscriptiosinensis, lobbii, lueddemanniana, mariae, modesta, parishii, sumatrana, tetraspis, venosa, violacea,
wilsonii, zebrina
slight
aphrodite, bastianii, borneensis, celebensis, cornu-cervi, doweryensis, equestris, fasciata, gibbosa, javanica, kunstleri,
lamelligera, lindenii, lowii, mannii, pantherina, philippinense, schilleriana, speciosa, stuartiana,
free
appendiculata, chibae, cochlearis, fuscata, maculata, micholitzii, minus, pallens, pulchra,
sanderiana, viridis,

 Whether the scent is pleasing or not may depend on individual preferences so it is hard to measure. P. violaceaP. lamelligeraP. hieroglyphica and P. gigantea have a citrus fruit fragrance, while, P. corningiana, P. floresensis, and P. sumatrana have an old-fashioned powdered soap fragrance.

TOP


Leaf Morphology

 The genus Phalaenopsis as epiphytes grows in both tropical monsoon forests and rainforests. The vegetation that survives in the dry season must adapt to the stress of desiccation by means of storing water in its leaves, stem, and roots. Further, it needs to minimize transpiration loss. Genera Bulbophylum, Cattleya, and Laelia, for example, mainly store water in the stems (bulb), while Phalaenopsis has no such bulb structure in its stem, so it must store water mainly in the leaves and roots. Thus, many Phalaenopsis have thick succulent leaves covered with a cuticular layer to prevent transpiration from the leaves. This cuticular layer prevents not only water evaporation but also pathogen intrusion and UV ray damage.

 The leaf composition means that they have the highest transpiration. This characteristic leads to defoliation of some species in dry or cool seasons. The leaves of Phalaenopsis are classified into two morphologies. At high altitudes (> 1,500 meters) in monsoon climates, there aren't many leaves; instead, the roots grow very long and contain chlorophyll. This structure enables plants to survive the dry and cool seasons without leaves. The species of subgenus Aphyllae, e.g., P. wilsonii, P. honghenensis, and P. braceana, are grouped into this environment. Both indeciduous and semi-decidious morphologies often appear in this group in artificial environment. This is because there is no stress from dryness or cool temperatures in the greenhouse throughout the year.

 The Genus Phalaenopsis stores moisture and photosynthesis-generated sugar in its leaves and roots, respectively, and could survive as long as the leaves are alive, even though the roots may have been damaged from partial cutting or from dryness sustained during overseas shipping. It regenerates roots and new leaves when the humidity and temperature are appropriately managed. On the contrary, it is hard to recover if the leaves sustain major damage.

  P. modesta and P. fimbriata have the thinnest leaves in Phalaenopsis genus; however, they are not indeciduous species. This structure has been developed to enable the plants to survive in the high-moisture rainforest all year round, where it doesn't need to store water in the leaves. Most Phalaenopsis have leaves that are dark green on the adaxial side and pale green on the abaxial side. The shape is oblong-oblanceolate to elliptic-obovate and tapered to the base. Some, e.g., P. sanderiana and P. philippinensis have tones of mixed brownish-red with green. Others, e.g. P. schilleriana,and P. celebensis are marbled in silvery gray and purple on the adaxial and abaxial sides, respectively. The colorful leaves on these foliage plants make them well worth keeping for ornamentation.

  Figure 7 shows the typical leaf morphologies - P. thalebanii、(upper left), P. bellina f. coerulea (lower left), P. schilleriana (center), and P. gigantea Kalimantan (right). In its natural enviroment, P. gigantea develops leaves over 50 cm long. Genus Phalaenopsis consists of monopodial epiphytes. Two types of stem are found those that grow upright and those that grow horizontally. To conform to the direction of the stem, the leaves of the former type develop so the adaxial side is facing up, and the right and left leaves are opposite each other (upper left). The leaves of the latter type are laxly arching-pendent (lower left, center, and right).

 There are very few species that have the characteristics to grow upright stems, e.g., P. thalebanii and P. cornu-cervi. The majority of species have leaves that grow pendulously in nature. This morphology can also be found when planting them on cork, an osmunda slab, or in a basket in horticulture.


Fig. 7 Leaf Morphology

 The surfaces of leaves growing on upright stems grow perpendicular to the sunlight. Thus, the leaves of the upper layer shade the lower leaves from the light. However, the leaves grow at alternating points on the stem rather than directly above each other; this leaves clearance between them on the same side so that the lower leaves receive oblique lighting more or less. However, when planting species with pendent leaves in a pot, the leaves often touch and overlap, and the leaves at the lower layer do not receive adequate light, which causes distorted growth. In contrast, the species with pendent leaves that are planted on cork develop with their leaves inclining alternately to the right and left, so both old and young leaves can receive the same amount of light from the sky.

 In countries near the equator, plants with upward stems receive sunlight that is perpendicular to their leaves, while plants with pendent leaves receive sunlight that is parallel at high noon. Observing these leaf morphologies, it is assumed that, e.g. P. cornu-cervi (the former type) grows in leafy forests at relatively low elevation, where sunlight from all directions filters through the foliage of surrounding trees, while, e.g. P. gigantea (the latter type) grows in the canopy layer where it receives strong sunlight in the late morning but scatters oblique light through the foliage in the morning and late afternoon.

 The thick succulent leaves (e.g. P. gigantea, P. bellina, P. pantherina, P. cornu-cervi) might be the evolutionary consequence of surviving and adapting to the xerophytic conditions in dry or low- rainfall seasons. Many Phalaenopsis species inhabit the riversides or the edge of marshes in the tropical rainforest, where a high level of humidity is maintained regardless of fluctuations in rainfall. In this environment, the leaves develop relatively thinly and often have undulations (P. modesta, P. fimbriata, P. javanica). In the rainforest, due to the multiple vegetation layers, a wide variety of leaf morphologies can be found, despite being at the same point on the map.

 The species: P. wilsonii, P. honghenensis, P. braceana, etc. inhabit mountainous regions above 2,000 meters in elevation, which have dry or cool seasons due to the subtropical monsoon climate. They drop the leaves in the cool season to avoid excessive transpiration. Their leaves are small and sparse (2 - 4 leaves). As shown in Fig. 8, P. wilsonii - a deciduous plant - develops very long and flattened roots out of proportion to the leaves. This type of species is adapted to being planted on cork or an osmunda slab and are not suitable for use with sphagnum in horticulture. This is because the root contains the chlorophyll and needs bright light for photosynthesis, especially in early spring when the temperature changes from cool to warm. With this background, it needs to be kept for 2-3 months at temperatures around 10C and receive light with almost the same amount of brightness as for the Cattleya before spring comes in order to achieve inflorescence.

  It is recommended that the hybrid Phalaenopsis be shaded from about 70% of sunlight. However, if the native Phalaenopsis is placed under 70% shade all through the year, except for P. tetraspis and P. fuscata, it could not grow big and healthy. Lighting at the same level as for the Cattleya, which might be too strong for a hybrid, is appropriate for the native species. Many species e.g. P. cornu-cervi, P. violacea, P. gigantea grow twice the size due to the strong brightness (ventilation is also very important under bright lighting). The brightness also produces many flowers. Balancing the quantity of light and the amount of CO2 might lead to the probability of obtaining the first flowering in a species that never flowered in the past.


Fig. 8 Subgenus Aphyllae (P. wilsonii)
 

 Tables 3 and 4 respectively indicate the thickness and the texture of leaves. The thickness rarely varies due to geographical conditions in the same species, except for a few. For example, P. equestris var. rosea has a relatively small number of thin leaves, while P. equestris var. leucaspis has leaves that are large and thick, nearly the same as P. cornu-cervi and P. amabilis.

Table 3 Thickness of Leaves
Thickness
Species
Remarks
Thick
amabilis (Taiwan), bellina, cornu-cervi, fuscata, gigantea, kunstleri,
lamelligera, lueddemanniana (Mindanao), pantherina, philippinense, sanderiana, schilleriana,
stuartiana, venosa, viridis,
Medium
amabilis (java), amboinensis, aphrodite, borneensis, celebensis, cochlearis, corningiana, doweryensis,
equestris, fasciata, lindenii, maculata, mannii, mariae, micholitzii, parishii, pulchra, speciosa,
sumatrana, tetraspis, violacea (sumatra, malaya),
Thin
appendiculata, bastianii, chibae, fimbriata, deliciosa, floresensis, gibbosa, hainanensis, hieroglyphica,
honghenensis, inscriptiosinensis, javanica, lobbii, lowii, modesta, pallens, stobartiana,
violacea (mentawai), wilsonii,
In area ratio, gibbosa is thick and subgenus aphyllae is medium

 Phalaenopsis leaves are roughly classified into two textures: solid and marble. The solid leaf is further divided into green and bistre green colors. Table 4 lists the species according to these types. Figure. 9 shows the marbled leaves of P. celebensis, P. lindenii, P. Philippinense, P. schilleriana and P. stuartiana from left to right. The common feature of these leaves is that they are pendent.

Table 4 Marbled Leaves
Pattern
Species
Remarks
Marbled
celebensis, lindenii, philippinense, schilleriana, stuartiana,
stuartiana has a solid type
Bistre green
amabilis, chibae, deliciosa, philippinense, sanderiana
amabilis in Borneo. philippinensis and deliciosa are partly.


Fig. 9 Leaves with Marbled Patterns

Table 5 Leaves with Downward, Undulation and Upward
Morphology
Species
備考
Pendent
amboinensis, bellina, celebensis, cochlearis, corningiana, deliciosa, doweryensis, fimbriata, floresensis, fuscata, gigantea, inscriptiosinensis, kunstleri, lindenii, philippinense, sanderiana, schilleriana, speciosa, stuartiana, sumatrana, tetraspis, venosa, violacea, viridis, zebrina
Undulation
deliciosa, fimbriata, inscriptiosinensis, violacea (mentawai),
varied in habitats
Upward
amabilis, aphrodite, bastianii, borneensis, chibae, cornu-cervi, delicata, equestris, fasciata, hieroglyphica, javanica, lamelligera, lueddemanniana, maculata, mannii, mariae, micholitzii, modesta, pallens, pantherina, pulchra,

 The thickness of the leaves indicates important information for cultivation. Species with thin leaves inhabit areas with moderate light that are consistently warm and moist throughout the year. In contrast, species with thick and pendent leaves are desiccation tolerant and are exposed to bright light and arid conditions. Thus, the former is preferable in high humidity conditions, while the latter is preferable in sharply different environments with a wet and dry cycle. Lighting at about the same level as for the Cattleya is important for both types of leaves.


Roots

 The roots of Phalaenopsis are aerial and prostrate epiphytic, which allows it to hold on to the host tree, absorbing water and storing nourishment. In horticulture, three root configurations are observed: (1) outshooting in the air with cylindrical forms that are unbranched and slightly wrinkled on a silvery-white exodermis, (2) appressed prostrate to the host trunk and exposed to the air with half side, hog-backed, wrinkled, and with a silvery-gray exodermis, and (3) appressed, with a heavily wrinkled, ribbon-like exodermis. These root morphologies might depend on the compost - sphagnum, cork, and mixed container - in horticulture. The root tip is about 5 - 10 mm long and has various colors as shown in Fig. 10 : light green (P. violacea), ocher (P. celebensis), mahogany (P. schilleriana), and camel (P. amabilis). The species in item (2) includes P. cornu-cervi, and P. pantheriana, which have thick cylindrical roots, whereas the ones in item (3) include many species, e.g. P. schilleriana, and P. stuartiana. The roots are generally unbranched, although exceptional cases occur when the tip is cut or necrotized.

 The species that are appressed to a host trunk with ribbon-like roots are more adaptable for mounting on cork and osmunda than in a pot in cultivation. On the contrary, the cylindrical and thick root - e.g. P. cornu-cervi, P. mannii - takes time (one year or more in BS) to stick to a host stem, so planting in a pot is preferable. The root tissue sticks to the host stem by the dense root hair that grows near the root tip, as shown in Fig. 11. The hair is 0.5 mm long or less and comes out on the surface opposite the sunny side. In aerial conditions, it undergoes regression in the old exodermis but only comes out around the tip (with a few exceptions).

 When planted in a pot with a high density mix-container in which the roots are placed in an obligate pseudo-terrestrial environment, the root exodermis of some species, e.g. P. schilleriana, becomes cylindrical, semi-translucent, and a white or pink color, despite having wrinkled and ribbon-like shapes on the host stem when exposed to the air. Whenreplanting from a container such as a pot to cork or an osmunda plate, the previous roots grown in the pot will never stick on the new host; only new roots can cleave, and deform to a wrinkled and ribbon-like shape.


Fig. 10 Root Morphology

 After being stuck on the host, the two kinds of roots appear on the side exposed to air: roots with hog-backed, white wrinkles that are parallel to the extension direction of the root (e.g. subgenus Zebrinae such as P. sumatrana, P. tetraspis), and ribbon-like, silver-gray roots with heavy and bumpy wrinkles (e.g. P. schilleriana, P. celebensis). Most Phalaenopsis species have the latter form.

 It is often observed that the roots grow aggressively in the air apart from the host. Whether the roots would stay inside or grow out of the pot (in horticulture) is assumed to be influenced by the humid environment surrounding the pot. Phalaenopsis roots exhibit hydrotropism. Thus, if steady and adequate humidity was provided outside of a pot or there was extreme desiccation in the pot, the roots might grow outward; otherwise, they would stay in the pot. Another possible cause of roots growing outward from the pot is placing them in an unsuitable container or material in the pot.

 The roots grow longer in bright conditions and are sluggish in dark conditions, exhibiting the same pattern as the leaves. The root morphology of many species mounted on cork or osmunda, (e.g. P. sumatrana, P. floresensis and subgenus Polychilos) shows many roots that are elongated upward or horizontal, and some (e.g. subgenus Parishianae) that grow all around. This pattern might arise due to the instinctive reaction to attach itself securely on the host as early as possible.

 The roots of Phalaenopsis are said to be a hydrotropic. Then, the majority of roots growing on an osmunda plate (with the lower part wetter than the upper part) should grow downward. Based on the horticulture experience, only P. modesta shows this behavior; most species, when stuck on the upper part of the plate, will develop root that grows in all directions.

 The roots do not display phototropism nor exhibit negative phototropism, as far as horticultural observations have indicated. Figure 10 shows P. speciosa on cork (left) and root tips with four color variations (right).

 Figure 11 shows a closeup picture of the root tip of P. amabilis. Highly dense root hairs like glandular trichomes are observed on the bottom and dark side. The hairs are 0.5mm or shorter, and they get into the aperture on the bumpy surface of the host stem. The hairs might have different characteristics from the terrestrial plant. Although individual hairs have no stickum, the total adhesive force is strong enough to rip the root itself down. 

 The surface exposed to the air does not have any root hair, but rather a silver or silver-gray wrinkled surface. When potting in a mixed container, the hair grows on the contact surface with the container. By putting the hair with the host surface, the hair grows appressed to the host, and the cylindrical shape (as shown in Fig. 11) is transformed into a flat.

 The root tip of the shiny side is light brown that changes to white as it increases in length, while, it is white greenish yellow on the opposite side. Thus, it can be assumed that the root can detect the direction of light, and it divides its functions into the two tasks of absorbing water and oxygen on its shiny side (the surface exposed to air), increasing the superficial area by the wrinkled surface, and clinging to the host with the dense hairs. This morphology of Phalaenopsis might be common in most epiphytic plants.


Fig. 11 Dense Hairs on Root Tip

Inflorescences

 The flower stalk of Phalaenopsis species bores through the leaf stalk and spindles forming the axillary bud and the floret primordium on nodes. The apex of the flower stalk exhibits phototropism and extends in the direction of the light source. It looks as if the directional growth of the stalk is remarkable in the species belonging to the section Phalaenopsis. The axillary buds at the under part of inflorescence shoots go dormant, and the buds at the upper part develop into floret primordia. It is often observed that a few axillary buds at the upper part turn into keikis (plantlets growing from one node along the inflorescence shoots). The incidence of keiki is higher in native species than in hybrids, especially in the lueddemanniana group (e.g. P. pulchra, P. pallens), and P. equestris often puts out keikis. There are two shapes of inflorescences: cylindrical (e.g. P. sumatrana), and flattened (e.g. P. cornu-cervi), in which the stalk is arched and extended, with nodes at equal intervals (e.g. P. amabilis), dense intervals (e.g. P. equestris ), and branched (e.g. P. schilleriana).

 The environmental conditions to induce inflorescences has been elucidated for the improved hybrids between the species of section Phalaenopsis(e.g., P. amabilis, P. schilleriana). According to reports, Phalaenopsis hybrids generate inflorescences after 6 - 8 weeks at temperatures of 25C or less and lighting of 12 hours or more a day. The low temperature in the daytime and the large volume of light volume are more important than the low temperature at night. The number of inflorescences increases corresponding to the amount of time they are exposed to irradiated light and decreases at temperatures of 21C or higher at night. The generation of inflorescences is suppressed at 28C in the daytime and 18C at night, and cannot be observed at 30C in the daytime and 21C at night.

 It is not clear whether these conditions are applicable for the majority of native Phalaenopsis species distributed in diverse habitats. The P. amabilis complex, which flowers from February - March, conforms to the above conditions. However, observing the flowering periods of various species, it seems there is no unique and quantitative value to produce the inflorescences. P. wilsonii in the subgenus Aphyllae requires a temperature of about 10C in the daytime and a lot of light at the roots for a few months, while many species (e.g., P. bellina) generate the flower stalk at a rather high temperature but with a 10C difference between day and night temperatures. Forthe subgenera Polychilos and Phalaenopsis, which comprise 80% of species, two factors are directly involoved with inducing the flower stalk - large light volume and low temperature (25C or less) in the daytime, or a difference (around 10C) between daytime and nighttime temperatures.

 Figure 12 (left) shows the rare sight of P. pulchra where the flower and the keiki are growing simultaneously at the tip of the inflorescences. Phalaenopsis does not usually produce a lateral bud from the stem. Figure 12 (right) shows P. amabilis, in which the erumpent lateral bud appears at the base of the stem. Such morphology is rarely observed, especially in the native species where the top of the stem has been damaged or has experienced a disturbance in growth. In this case, the lateral bud will eventually grow bigger and more rapidly than the original stem. The keiki is likely to develop under a higher temperature than expected for a floret primordium.

 There are two colors of inflorescence - green and dark brown - which reflect the color or texture of leaves. The inflorescences are dark brown in species with leaves (adaxial or abaxial side) that are dark green, purple, marbled or brown, while it is green in the fully green leaves. P. amabilis and P. equestris are exceptions: they have both colors, which vary depending on the region.


Fig. 12 Keiki and Lateral Bud
 The length of inflorescence varies by species. Figure 13 shows four types of inflorescences: the shortest stalk (1-2cm) of P. micholitzii (upper left), the flat, zigzagged stalk of P. lamelligera (lower left), a long stalk (50 cm or more) of P. violacea v. mentawai (center), and the longest stalk (1 m or more) of a pulchra (right). They bloom one by one on the floret primordia on nodes.

 The inflorescences may be used to identify the species and habitat. For example, P. violacea v. mentawai is a pale red-violet color. The P. violacea sold in the market has been improved to have various colors due to crossbreeding between selected species, so it is hard to identify the native or hybrid species. The native P. violacea f. Mentawai has inflorescences that are 50 cm long or more. If it were only 20 cm or less, as seen in a normal violacea, it might be a hybrid (except for young plants).

 Nowadays, it is becoming more difficult to identify the native or hybrid species because most suppliers do not know the breeding history nor maintain records of parent plants.


Fig. 13 Length of Inflorescences

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Geographical Varieties of Perianth

 Genus Phalaenopsis has several species with a widely distributed habitat (e.g. P. amabilis, P. cornu-cerviP. sumatrana ). These species have perianth forms that are slightly different based on their habitat. The factors typically used to identify the species - size and number of flowers - are not useful in this case because such appearances might vary due to, e.g., climate changes, fertilization, age, and individual variability. The lip and callus structures are considered to be useful factors for identification, as they are less affected by individual characteristics.

 Figure 14 shows P. amabilis, one of the most widely distributed species in Taiwan, the Philippines, Borneo, Malaysia, Java, Sumatra, New Guinea, and Australia. It has been used, as a parent species, for producing the commercial breed of this plant, which is now the most popular Phalaenopsis on the market. The sepals and petals are pure white, and the lip is yellow-white with red spots and bars on its base. This species does not grow in jungles with thick vegetation but in open forests, and it has flowers on the inflorescences of 1 m or more in nature. In horticulture, the inflorescences appear when the temperature is maintained at 18C at night and 25C in the daytime for 1-2 months, and it blossoms about 2 months after the outbreak of inflorescences.

 Figures 14 and 15 show six shapes of the perianth and midlobe of native P. amabilis species from Taiwan, Sumatra, Irja, Java and Borneo, respectively. The midlobes of the lips in these species are slightly different from each other - short and wide (Taiwan, Sumatra and Irja ), or long and thin (Java, Borneo). The base of the petal is slender (Irja , Borneo) or short (Taiwan, Sumatra), and the perianth size is relatively small (Taiwan to Irja ) or large (Java and Borneo). Going southward, the petal changes its shape from small and rounded to a large rhomboid shape.


Fig. 14 Perianth Varieties of P. amabilis in Different Areas

Fig. 15 Callus Varieties of P. amabilis in Different Areas

 As described above, the flower size and shape are not useful for identifying the habitat because there are too many factors that affect the size and shape. It may be necessary to include the lip shape to get a closer idea of the identification. P. amabilis in different areas have been investigated by DNA analysis, and genetic distance has been observed among - Palawan, Sabah, Mentawai, rosenstromii, moluccana, Timor, and Java - which are the areas related to evolutionary trends . Most Phalaenopsis are endemic species except for a few, e.g., P. amabilis, P. sumatra, P. violacea, P. cornu-cervi, and P. deliciosa, so the majority of Phalaenopsis do not exhibit differences in shape due to geography. On the contrary, some species among their sister relations are difficult to identify, even by professionals, because of the appearance of the perianth. Furthermore, callus structures are often found in imported species that have never been seen before. It is not apparent where such callus structures come from: an anomaly, new habitat, natural hybrid, or artificial crossbreed. Scented and non-scented characteristics in the same species are also observed in e.g., P. cornu-cervi, P. modesta, and P. hieroglyphica. Further research on the fragrance components is expected.


Geographical Varieties of Leaves

  Phalaenopsis is a species in which a variety of colors and shapes are observed in the leaves. However, it is difficult to define the geographical background from the leaf shape. The leaf shape is susceptible to the effects of the environment even in horticulture. Figure 16 shows some leaves of Phalaenopsis. P bellina (top left) has thick, succulent and elliptic-obovate leaves that are 30 cm long or more in natural environments. To grow leaves longer more than 30 cm would be rare in cultivation, as they are typically shorter and more rounded. This would indicate that steady and sufficient watering and fertilizing are supplied.

 P. violacea v. mentawai is classified together as a P. violacea species. However, the leaves of this species have quite a different shape from those in other regions (Peninsular Malaysia and Sumatra). The Mentawai's leaves are thin, elongated (30 cm or more) and undulated, as shown in Fig. 16 (top right). Nowadays, due to well-practiced crossbreeding between P. bellina and P. violacea, the products which have leaves with mixed features are often found in the market. The problem is these hybrids have been sold by the name of P. violacea or P. bellina.

 Figure 16 (lower) shows P. gigantea. The main habitat for this species is in Borneo and partly in Sumatra (although there is a theory that P. gigantea does not inhabit Sumatra). The leaves from P. gigantea in Sumatra and Borneo (Sabah) are respectively elongated and rounded. The total size of the plants in Sumatra are smaller than those in Borneo. P. gigantea in Kalimantan has a size and shape in between those in Sabah and Sumatra.

 The growth of leaves depends significantly on the cultivation environment. To obtain big and healthy leaves, adequate fertilization and a lot of light must be provided. Wild plants or native species require a very bright cattleya-like light level with sufficient air movement so the leaf temperature is not too high.

 One curious morphology is that wild species become much bigger than artificially cultivated species even though the fertilization, light, temperature and humidity levels in the cultivation environment are provided at more appropriate levels than in the natural environment. It is assumed that the wild species might have to survive by storing water in the leaves to avoid dehydration in the dry season. Furthermore, the wild species might have to produce sources of nourishment by photosynthesis in the epiphytic condition in which nourishment cannot be obtained from the soil. In these environments, the plants might grow larger leaves because the larger leaf surfaces can receive more light and store more water. The leaves of P. gigantea from different regions grow to the same size and develop similar shapes after 5 or 6 years in cultivation, which tells us that the environment exerts a strong influence on the leaf size and shape.


Fig. 16. Leaf Shape Varieties

Similar Species

1.P. cornu-cervi Group 

 Phalaenopsis has some species - in the subgenera Polychilos and Aphyllae - that are difficult to identify from the shape and texture of the perianth. For example, P. borneensisP. cornu-cerviP. pantherinaand P. lamelligera in the section Polychilos have very similar forms in which clear differences are hard to find. Due to the strong similarity, some opinions are that these species are conspecific. Figure 17 shows the flowers in the P. cornu-cervi complex of section Polychilos. The perianth lobes seem slightly different from each other; however, their textures and shapes might be within a range of individual variations. Only the shape at the apex of the midlobe shows unique characteristics.

Fig. 17 Species of Subgenus Polychilos

 The species 'unknown' in Fig. 17 (far right) came from indonesia labeled as a P. cornu-cervi. In the website "Especes De Phalaenipsis"(see reference page on this site), a flower that looks nearly the same as the "unknown" species is posted and identified as P. borneensis. I suspect that this is not P. borneensis, though P. cornu-cervi (Fig. 17; far left) and the unknown species have midlobe tip shapes that are sagittate and lunate, respectively. The lunate tip-shape of the unknown species is rather similar to P. pantherina (center). The remarkable difference between the unknown species and P. cornu-cervi is that the former has a coconut scent, while P. cornu-cervi generally has no scent at all.

 Figures 18 and 19 show the lip structures of the corresponding species in Fig. 17. The lateral lobes have been removed from the lip to make it easy to see the callus.

Fig.18 Structures of Midlobe Tip of Species in Fig.17
Fig. 19. Callus Structures of Species in Fig.17

 The features of the lip and callus forms of the species in Figs. 18 and 19 are summarized in Table 6. Each item in Table 6 is listed as follows: (1) the tip shape of the midlobe, (2) the center area of the tip, (3) the neck of the midlobe, (4) the rod-like apophysis at the base of the midlobe, and (5) the callus (posterior side).

Table 6 Features of Lip
Species
Midlobe tip (1)
Tip pad(2)
Tip pad(2)
Midlobe length(3)
Rod-like apophysis(4)
Callus (posterior)(5)
scent
cornu-cervi
sagittate and lunate
flat plain short sharp edge glandular free
lamelligera whale's tail concave plain short spire denticle + glandular lush and spicy
pantherina wing convex trichome long sharp denticle grass
borneensis sagittate gentle convex plain short flat denticle + glandular
unknown wing convex plain short sharp denticle caprylic

  Observing the pictures in Figs. 18 and 19, P. lamelligera and P. pantherina have clearly different midlobe (1) and callus shapes from other species. The glandular callus (at posterior) of P. cornu-cervi is different from the others (bifid plate). The unknown species (far right) is from Indonesia, possibly Java, and has a unique wing shape of the midlobe tip that is similar to P. pantherina, although the length of the midlobe (3) is shorter than the P. pantherina. The pad (2) with trichome is only seen in the P. pantherina. It is possible that the unknown species is a natural hybrid between P. cornu-cervi and P. pantherina. However, it is difficult to explain why it has a scent that neither of those species has.

 In the classification of the P. cornu-cervi complex, only the P. pantherina has explicit criteria. One well known website defines that P. lamelligera and P. borneensis as crossbreeds. Although it is said that there is no substantial reason to distinguish between P. lamelligera and P. cornu-cervi, as seen in Figs.18 and 19, these two strains are different from each other not only in the callus structure but also in their scent. Further research is expected for the classification of P. cornu-cervi complex.

 Table 7 lists the species that are difficult to identify and trace the parents. P. amabilis and P. equestris may be included in this list.

Table 7 Species Difficult to Identify
Species
Remarks
possible geographical hybrid, hybrid with bellina
lueddemanniana
similarity to amabilis formosana (Taiwan)
aphyllae亜属

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