|The great variety of climate, land forms and vegetation types in the continent of Asia has made available many different habitats for orchids. Plants which tolerate extremes of light and temperature are common at the high altitudes, while lower down there are many different epiphytes and shade-loving terrestrial plants. They exhibit a great diversity of form, ranging in size from tiny species of Taeniophyllum, with flowers smaller than a pin head, to the world's largest orchid plant, Grammatophyllum speciosum, whose pseudobulbs can grow up to 10 m long.||
Dendrobium hybrids in Singapure Botanic Gardens
Two of the best known terrestrial orchid genera, Pleione and Paphiopedilum,
are both from Asia and well represented in the Kew collection. There are
also many less familiar ones, such as Acanthephippium, Ludisia and Tainia.
|The Pleiones come from the Himalayan region, from Nepal eastwards, to Taiwan, and grow in the mats of moss and fallen leaf litter that accumulates in the cracks among rocks and on mountain slopes. A few are epiphytes. Their root run is quite shallow, and the drainage is very good in their natural environment so at Kew they are grown in half pots, 6 cm deep, in an open, bark-based compost. For ease of cultivation pleiones can be divided into two groups: the autumn flowering species require somewhat warmer conditions and are grown in a greenhouse with a winter night minimum temperature of 14ºC (52ºF), whilst the spring flowering species are usually kept in a cold greenhouse, minimum temperature 7ºC (40ºF). Pleiones finish flowering in December. Their new leaves and roots start to grow by mid-February, so annual repotting is carried out in January.|
Most of the Pleione species are now in cultivation at Kew, the collection
having been assembled over many years while Peter Hunt, Phillip Cribb and
others have worked on the genus. This research resulted in the publication
of the widely acclaimed book The Genus Pleione, by Cribb and Butterfield
Pleione humilis begins the flowering season at the end of February with its pale pink sepals and petals and a white frilled lip with reddish brown streaks. It is easily recognised by the distinctive conical, pointed pseudobulbs. Pleione formosana is a very varied species. The type has rosy pink sepals and petals and a white lip with raised yellow markings and orange blotches; other forms have sparkling white flowers with a few lemon yellow markings on the lip. Several of the named cultivars are grown, including 'Blush of Dawn' and 'Oriental Grace' and also some hybrids bred from Pleione formosana including the grexes Versailles, Alishan and Tongariro.
|The yellow Pleione forrestii is of great interest
to hybridisers looking for a new range of colours but is a charming addition
to the display in its own right.
By crossing some of the spring and autumn flowering species, winter flowering hybrids have been produced, such as the deep pink Barcena. These hybrids are grown at the warmer temperatures favoured by the autumn flowering species. The spring flowering pleiones can be gently forced into flower early in the
|The lovely jewel orchids in the genera Anoectochilus, Ludisia and Macodes have the reputation of being difficult to cultivate. They require warm temperatures with a winter night minimum temperature of 16ºC (60ºF), shade from direct sunlight, and a high relative humidity in order to grow well. Their succulent stems are very attractive to slugs and, as a growth of many months can be eaten in one night, constant vigilance is needed. In the wild, the creeping stems of the jewel orchids thread their way through cushions of moss and fallen leaves. At Kew they are grown in shallow seed trays filled with about 4 cm of well drained compost so that their stems can spread naturally over the surface.||
|Most orchids are grown for their attractive flowers, but the main interest
in growing the jewel orchids is for their leaves. Ludisia discolor has
reddish green leaves overlaid with bronze and a velvety bloom. The veins
are a delicate network of pink. This species flowers readily and produces
flower spikes up to 30 cm tall throughout the winter and spring. The white
flowers have yellow markings and a beautiful, penetrating perfume. Unfortunately
the widely grown cultivar, Ludisia discolor 'Doris Stein' is not scented,
but it has larger flowers and leaves than the wild species.
Macodes cominsii from the Solomon Islands has a fleshy, heart shaped leaf, which is a pale green colour with purple veins and markings.
Acanthephippium sylhetense, also from
Thailand as well as India and the Himalayas, is grown nearby. Its bold
plicate leaves rise to 90 cm from the stout conical pseudobulbs. The short
racemes grow in early spring bearing up to six flowers which are cup-shaped
and waxy in texture. The long-lasting flowers are cream with purple markings
and produce a beautiful scent.
The genus Calanthe comprises over 120 species which are predominantly terrestrial orchids. Representatives are found throughout the old world tropics Africa, Asia, Australia and the Pacific area), although the majority of species occur in Asia. The deciduous calanthes all have stout, silvery-green pseudobulbs and lush foliage which grows during the spring and summer. In the autumn, as the leaves fall, the flower spikes grow rapidly from the bases of the newly completed pseudobulbs. They reach 1/2 m in height and the pretty colourful flowers last for many weeks. New leaf growth begins soon after the flowers fall in spring. During their dormant period these species require no water at all, even though they are in full flower, the moisture in the humid air around them being enough to prevent the pseudobulbs from shrivelling. As soon as the flowers fade, the pseudobulbs are repotted into a compost made of peat and perlite with added hoof and horn fertiliser, for calanthes are heavy feeders. New roots grow rapidly into the compost and the fresh green leaves soon expand.
This group of calanthes is grown in a sunny position in a warm glasshouse with a winter night minimum temperature of 18ºC (64ºF) and a high relative humidity. Calanthe vestita is the most vigorous of the species with leaves and flower spikes of up 1.5 m long. The individual flowers are up to 4 m across and are white with a crimson lip. This species occurs over a wide range from Burma through Thailand to Borneo. Calanthe rubens comes from Thailand and the Langkawi Islands and is rather smaller. Its flowers are dark pink, to 3 m across, while the centre of the lip is deep crimson fading to pink at the edge.
A number of Calanthe hybrids are grown for display in the Princess of Wales Conservatory. Calanthe Bryan has large cream coloured flowers with a greeny tinge and a deep crimson blotch in the throat. Calanthe Veitchii is one of the earlier hybrids with rosy pink flowers resulting from the cross between Calanthe rosea and Calanthe vestita. Deep rose red flowers are available on Calanthe Diana Broughton and its progeny.
The evergreen calanthes of China, Japan and the Himalayas may retain their leaves throughout the year, although the plants become dormant during the winter.
At Kew they are grown in a semi-shaded position, in a glasshouse with a winter night minimum temperature of 13ºC (55ºF) and a relative humidity of over 75%. They are repotted in the spring in a terrestrial compost with plenty of leaf mould. Most species flower in the spring and summer. Unlike the deciduous calanthes which have long arching flower spikes, the evergreen species have an inflorescence which grows erect, just overtopping the leaves, and the raceme bears several flowers.
Calanthe arisanense starts the flowering season in February and has white flowers with a hint of mauve, each about 3 m across. Calanthe brevicornu is from Nepal and has pale lilac petals and a purple lip with yellow markings. Calanthe discolor, from Japan and Korea, is purple with a pale pink lip.
Calanthe argenteostriata is a warm-growing, evergreen species requiring
a winter night minimum temperature of 18ºC (64ºF) and a high
relative humidity. It is named for its deep glossy green leaves which have
broad silver stripes running longitudinally along the veins. Each leaf
is up to 30 m long and 15 m wide and a clump of foliage is a striking sight.
The inflorescence grows to a height of up to 60 m and has about a dozen
small white flowers. This species was discovered on Triangle Mountain in
Guangdong province in China and is still not common in cultivation.
|There are currently considered to be some 60 species
in the genus Paphiopedilum most of which are cultivated at Kew. Ever
since their discovery and introduction, paphiopedilums have been sought
after by collectors and their curious flowers seem to excite more interest
than any other genus of orchids. In recent years a representative collection
of species and hybrids has been brought together at Kew as a prerequisite
for the monographic study of the genus by Phillip Cribb published in 1987.
One gram of crushed dolomite limestone is added to each litre of this mixture to raise the pH slightly and a little chopped sphagnum moss is incorporated for those species known to inhabit very moist areas.
Paphiopedilums are readily recognised by their basal fans of leaves from the centre of which the flower scapes emerge. The leaves vary greatly, some being long, strap-shaped and a uniform deep green, such as those of Paphiopedilum rothschildianum, whereas others have shorter leaves which are dark green mottled light green or silver, such as Paphiopedilum wardii and Paphiopedilum delenatii. The flowers have a conspicuous dorsal sepal, the familiar slipper shaped lip, two outstretched or pendulous petals and a shield?like structure at the apex of the column called the staminode. Within this form, however, there is great variation in shape and especially in colour.
A tour of the paphiopedilum collection at Kew will reveal flowers at any time of the year. All the mature plants flower regularly at their own season, and the flowers will last for up to two months if they are not pollinated. Paphiopedilum gratrixianum, from Laos, is at its best in December and January. It has a shiny, pale brown lip and brown petals with maroon veins. The dorsal sepal is pale green fading to white at the edges and marked with large, raised, maroon blotches. This species is quite distinctive, even when not in flower, for the narrow, pale green leaves are covered in maroon spots at their bases. Paphiopedilum appletonianum also flowers at this time on very long peduncles, each bearing a single bloom which has a pale pink lip and petals which broaden out at the tips to resemble rosy pink ears. The dorsal sepal is pale green marked with maroon veins.
The unfortunately named bubble gum orchid, Paphiopedilum micranthum, flowers in March and April. Its dark green leaves, finely chequered with pale, silvery green, are stiff but very attractive, and the flower is delightful. The petals and sepals are short and wide, rounded, pale green tinged with pink and veined with maroon. The lip is very large, almost spherical, and is white with a rosy pink blush. Paphiopedilum micranthum originates from the limestone hills of Yunnan in China, not far from where the golden Paphiopedilum armeniacum occurs. Sadly, both these species come from restricted areas in China and may now be very rare indeed due to over collecting. This places an obligation upon growers to propagate new plants from seeds and divisions, so that collectors do not need to remove more plants from the wild to supply the increasing demand for such attractive orchids.
The early summer brings Paphiopedilum rothschildianum into flower. Its petals may span 30 cm and are a creamy colour with maroon veins and maroon warts and hairs. The dorsal sepal is also cream, veined with maroon, and the lip is rosy pink veined with maroon. This spectacular species bears up to five flowers on each inflorescence about 60 cm above the waxy, strap shaped leaves. Paphiopedilum philippinense flowers a little later and also has several flowers in each inflorescence. In this species the petals, which are pale purple and green, hang downwards and twist. The dorsal sepal is white with purple markings, and the lip is a yellowish green with purple veins. Paphiopedilum concolor is a Thailand species which flowers in late summer. Its rosettes of mottled leaves are interesting all through the year, and from August onwards it produces its rather solid, heavy-looking cream flowers which rest upon the foliage. The rounded petals and dorsal sepal are finely marked with many purple spots.
The autumn brings the cooler-growing species into flower. Paphiopedilum insigne from India has pale, narrow leaves, a broad, pale brown lip and pale brown petals with wavy edges. The dorsal sepal is white and green and heavily marked with purple blotches. Paphiopedilum fairrieanum has the most elegant white petals, boldly marked with maroon veins and hairs; the petals turn backwards at their tips. The dorsal sepal is white with a network of maroon veins and the lip is pale green. Every month brings different paphiopedilums into flower and, on the rare occasions when the collection can show no flowers, the many superbly mottled and shiny leaves give ample interest.
Terrestrials Epiphytes Back to the top
The epiphytic genus Taeniophyllum has diminutive flowers, scarcely larger than a pin?head. There are some 200 species, most of which occur in Asia. Like the members of the African genus Microcoelia, taeniophyllums have small brown scales instead of leaves and the process of photosynthesis is carried out in the green roots. Most members of this genus grow upon the twigs of rain forest trees and in cultivation they respond well to constant air movement, a high relative humidity, and a warm greenhouse with a winter night minimum temperature of 18ºC (64ºF).
The moth orchids, of the genus Phalaenopsis, are far more common. At Kew they are grown with equal success in pots of medium epiphyte compost or mounted on bark, but the mounted plants need more frequent watering and misting as their exposed roots dry out more quickly. Phalaenopsis enjoy shady warm conditions in a greenhouse with a winter minimum night temperature of 14ºC (61ºF). Their healthy, shining foliage is a pleasure to see at any time of the year, and the arching sprays of flowers are a welcome reminder that spring is on the way.
Phalaenopsis amabilis is known from a very wide area of Indonesia, New Guinea, Malaysia and northern Australia. At its best each inflorescence can reach up to 1 m long and carry 20 flowers each 10 cm across. The flowers are a glistening white with a yellow flush on the lip and red markings. Phalaenopsis stuartiana and P. schilleriana both originate in the Philippines and are similar in that they have long, narrow, deep green leaves which are marbled with silver. Phalaenopsis stuartiana has white flowers which are marked with yellow on the lip and liberally peppered with maroon spots. Phalaenopsis schilleriana has pale pink flowers with yellow markings and red spots on the lip.
Phalaenopsis mannii has plain green leaves and a short inflorescence containing up to six flowers which are star shaped and pale yellow in colour with brown bars across the segments. This species has a sweet fragrance and originates from Assam. Phalaenopsis cornu?cervi, from Indonesia and Borneo, has flowers of a similar colour but differs in its distinctively flattened rachis and orange markings on the lip.
The heavy hanging leaves of Phalaenopsis gigantea from Borneo can grow up to 60 cm long under the very humid conditions of their native habitat. Their rounded shape and waxy, grey?green colour make them instantly recognisable, While the inflorescence hangs like a bunch of grapes underneath the foliage. The large buds keep the grower in suspense for a week or more, then open to reveal a pale yellow or pink ground nearly obscured by heavy brown blotches.
The sad story of Vanda coerulea is typical of many beautiful orchids. First discovered in Assam in 1857, its' white or pale blue flowers with their bold network of royal purple markings made this species greatly sought?after by collectors. It is now a rarity, where once it grew in profusion, and such colonies that do exist are probably too small to maintain themselves naturally as their habitats have also been greatly diminished. This tragedy will be repeated for countless other species of orchids unless every effort is made to satisfy demand by propagating from cultivated plants rather than importing more plants collected in the wild.
Vanda coerulea, like many other vandas requires a lot of sunlight in order to induce flowering. Even at the height of summer only very light shading is needed. At Kew vandas are grown in slatted pots hanging from overhead wires because mature plants produce a profusion of aerial roots hanging down from the stems. A very coarse epiphyte compost is used. They are grown in the warmest greenhouse, with a winter night minimum temperature of 18ºC (64ºF), but many species, especially V. coerulea, would grow equally well in cooler conditions; they are kept in a warmer house than necessary at Kew because it is the only house where the maximum amount of light is available. Vanda tessellata, from Bengal, has pale green flowers up to 4 cm across which are tessellated with pale brown markings. Vanda tricolor var. suavis has white flowers marked with magenta blotches. The heady perfume from this species is almost overpowering at close range. Vanda lamellata from the Marianas Islands has rather slender flowers of a pale lemon colour in which the lateral sepals are ?streaked with red. Vanda dearei from Borneo is also a lemon colour but the petals are much fuller and more rounded than those of V. lamellata. The lip is a more intense yellow around the tip and white at the base.
The genus Aerides is closely related to the vandas, and vegetatively the plants are rather similar. At Kew these two genera are grown under the same conditions and in similar pots and compost. The waxy flowers of the Aerides species cluster along a short and pendulous rachis. They open simultaneously and are delightfully fragrant. Aerides falcata from India and Thailand has white flowers marked with striking magenta spots, while the Himalayan A. fieldingii has purple flowers with white markings. Aerides houlletiana, from Vietnam, has browny yellow flowers with orange markings at the tip of each segment.
One of the most widely grown genera of orchids is Dendrobium, which, at a conservative estimate, has at least 900 species, most of them in Asia. At Kew the Asiatic dendrobiums are grown in three different environments. The warmest and lightest greenhouse, with a winter night minimum temperature of 17ºC (64ºF) and a high relative humidity, houses the lowland tropical epiphytes which, in time, produce mighty clumps of tall canes. They are grown in clay pots filled with broken crocks and coarse epiphyte compost, and their white roots quickly encrust the whole pot. Dendrobium discolor, which comes from New Guinea, produces canes up to 2 m tall and inflorescences 30 cm long. The flowers are cream, gold or brownish and the petals have wavy margins. Dendrobium lasianthera, also from New Guinea, grows even taller, and each inflorescence has up to 20 flowers which are bronze with purple markings on the lip. Dendrobium antennatum is very small by comparison and has densely crowded pseudobulbs, 30 cm tall, with light green lanceolate leaves. The arching inflorescences grow up to 30 cm long and carry up to a dozen graceful white flowers. They have pink markings on the lip and the pale green petals form two upright 'antelope horns' above the flower.
Dendrobium nobile and its allies grow under intermediate conditions in a light, airy greenhouse with a winter night minimum temperature of 15ºC (60ºF). These species are grown in small clay pots of medium epiphyte compost. Dendrobium nobile has a wide range from China and Nepal to Thailand. Each pseudobulb grows up to 60 cm tall and its leaves are deciduous. The older canes remain leafless at any time of the year. The fragrant, long?lasting flowers are white with magenta tips to each sepal and a deep purple blotch in the throat. Dendrobium farmeri, which comes from the Himalayas, also grows well under these conditions, and has flowers up to 4 cm across which are pale pink with a soft yellow lip. Dendrobium primulinum, also from the Himalayas, as well as China, Burma and Thailand, grows in a hanging basket for it has a pendulous habit. It flowers on the old leafless canes and has white flowers tinged with pink and a pale yellow lip.
The third set of environmental conditions, cool intermediate, with a minimum temperature of 14ºC (57ºF), a relative humidity above 80% and very good air movement, is suitable for the 'alpine' dendrobiums from the mountains of Papua New Guinea. These form small creeping tufts of foliage among the surrounding moss on the cork oak bark on which they are mounted. The disproportionately large flowers peep out from amongst the leaves. Dendrobium subuliferum has fine grassy foliage with white flowers up to 1 cm across. Dendrobium alaticaulinum has flowers which are an intense orange colour at the tips, while the flowers of D. simplex are white dotted with purple on the outside and suffused with pale green inside. Dendrobium cuthbertsonii, which occurs in a wide range of pinks, orange, and scarlet, is probably the best known of this section.
There are about 44 Cymbidium species currently recognised, three of which are native to Australia and the rest range in habitat from the Himalayas to the humid forests of the Philippines. Cymbidiums are known to have been cultivated in China before 551 BC and became a symbol of superiority much admired by the nobility of the day. The first species to be grown in Europe was C. ensifolium, from China, introduced in 1778 by James Fothergill. The first hybrid to be shown at the Royal Horticultural Society was a cross between two Himalayan species, C. eburneum and C. lowianum, one clone from which received a First Class Certificate in 1889. Since then a huge range of hybrids has been bred and enjoyed. At Kew a small selection of hybrids is grown to provide displays of colourful flowers in the Princess of Wales Conservatory. These are grown under cool, light, airy conditions to give strong, hard foliage and regular flowering. The collection of Cymbidium species at Kew has been assembled in the last ten years for the research carried out by David DuPuy and Phillip
Cribb which was published in 1988 and is described in more detail in chapter 14. The collection is also of considerable interest to the hybridiser, for the possible introduction of desirable new characteristics, such as fragrance, into future hybrids.
A very warm greenhouse, humid and quite light, with a winter night minimum temperature of 18ºC (64ºF), suits the small group of lowland tropical species, which are mostly epiphytes. They are grown tightly potted in coarse epiphyte compost or in hollow logs made of cork oak bark which are then hung from the roof of the greenhouse. This method allows the pendulous flower spikes to be appreciated fully. Cymbidium finlaysonianum grows under these conditions and has clumps of hard, leathery, dark green, strap?shaped foliage. The pendulous flower spikes grow up to 1.5 m long and carry many flowers each up to 3 cm across. The flowers are a yellowy green shade with purple markings on the lip. Cymbidium aloifolium, from Sri Lanka, India, China and southeast Asia, has shorter leaves and a flower spike up to 60 cm long. Each flower is pale green, with brown markings down the middle of each segment, and has a red?brown lip.
The majority of Cymbidium species are grown under cool conditions with a minimum temperature of 11ºC (52ºF) and good air movement. Their colours, shapes and perfumes often surprise people who are only familiar with the larger flowered hybrids. Cymbidium insigne, from China, Thailand and Vietnam, has an erect flower spike up to 1.5 m tall with up to a dozen flowers at the top. Each flower measures up to 6 cm across and is white suffused with the palest pink. The lip is marked with deeper pink blotches. Cymbidium tracyanum, from Burma, is the first to flower, in October, and has an arching inflorescence up to 1.5 m long, densely crowded with large flowers which are a pale browny yellow colour greatly enlivened by deep red markings on the petals and lip. These flowers produce a heady perfume which easily pervades the whole greenhouse. Cymbidium devonianum, from the Himalayas, has characteristically rounded leaves and pendulous flower spikes of pale yellow flowers thickly streaked with purple. Cymbidium faberi var. szechuanicum from Nepal has slender grassy foliage with flower spikes up to 30 cm tall carrying several flowers which are a very pale green colour with red markings and a deep green lip with crimson streaks. Cymbidium dayanum from Thailand holds its flowers on short spikes close to the base of the leaves. The flowers are a starry shape and pale cream in colour with a bold red line along the centre of each petal and sepal and a red lip with yellow markings. One of the most striking species is C. elegans, which bears many flowered racemes of pale yellow, funnel?shaped flowers.
Epiphytes Back to the
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