Members of the genus Dendrobium are some of the most popular of all horticultural subjects. Many of the species are easy to grow, either in pots or on mounts. Plants can come in all sizes from as small as a grain of wheat (such as Dendrobium lichenastrum) to monster plants of several yards (m) in length (such as Dendrobium discolor or Dendrobium violaceoflavens).
The subjects for this article are, for the most part, of modest dimensions, and the only species that can get large is Dendrobium fairchildiae, where the pseudobulbs can get to about 5 feet (1.5 m) in length. All other species mentioned here would seldom be more than 2.5 feet (76 cm) in height or length.
Johannes J. Smith established the section Calcarifera in 1908, which he had separated from section Pedilonum. The main characters that distinguish the section are: the labellum is abruptly broadened from a narrow claw, while the mentum points away from the pedicel and ovary (suggesting pollination by insects). In most members, the pseudobulbs are slim or spindle–shaped and are often pendulous with thin–textured leaves along the stem, which become deciduous after a year or two. The inflorescence usually appears from the older leafless pseudobulbs with the flowers encircling the inflorescence and facing more or less horizontally.
The section Calcarifera has over 90 species. The center of distribution is in Sumatra, which has about 29 species; next is Borneo with 22 species; then the Philippines with at least 20 species, but I am aware of a further three new species waiting to be scientifically described; and Peninsula Malaysia with 17 species. These are mostly plants of humid tropical forests, which experience year–round rainfall and are found at low to moderate altitudes (sea level to above 5,000 feet [1524 m]).
A SELECTION OF SPECIES
Dendrobium arcuatum This species was named by Johannes J. Smith in 1905 in Die Orchideen von Java (The Orchids of Java). The specific epithet means bent or bow–shaped and possibly refers to the shape of the mentum (spur). The plant can reach lengths of over 3 feet (0.9 m) by about one–quarter of an inch (0.6 cm) in diameter. The flowers are about 1.25 inches (3.2 cm) in diameter. Each inflorescence can have up to six blooms. This species appears to be endemic to the Indonesian island of Java, where it grows as an epiphyte at elevations of around 2,000 feet (610 m).
[1] Dendrobium arcuatum ‘Myra’ CBR/AOS grown by Jordan Hawley. photograph from the AOS award archives.
2] Another example of Den. arcuatum.
Dendrobium boosii Jim Cootes and Wally Suarez named this species in 2011 in the Australian Orchid Review. The specific epithet honors a colleague of the two authors. The plant grows pendulously from a single basal growth, branching as the plant becomes older and can reach up to 2 feet (0.6 m) in length. The blooms are most attractive in their coloration in shades ranging from pale pink to pure white. The serrated edge of the colorful labellum is another attractive feature of this species. This recently discovered species has a limited distribution in the mountains of the island of Leyte in the central Philippine archipelago, and it has recently been found in the mountains of northern Mindanao. This particular form has a slightly different coloration to the form found on Leyte. It grows at elevations of around 2,000 feet (610 m) as an epiphyte.
[3] Dendrobium boosii.
[4–5] Additional examples of Den. boosii grown and photographed by Ronny Boos.
Dendrobium calicopis Henry Ridley named this species in 1903 in the Journal of the Straits Branch of the Royal Asiatic Society, Singapore. The specific epithet is from the Greek kalos meaning beautiful and the Greek opis meaning sight, so one would assume it means a “beautiful sight”. The stems are about 1 foot (30.5 cm) in length. Three or four flowers, each about 1 inch (2.5 cm) in diameter, appear on a short inflorescence. Blooms are white with a rosy tint. This species is known from Myanmar, Thailand, Peninsular Malaysia, and the Langkawi Islands, where it grows at elevations from sea level to 3,000 feet (915 m).
[6] Den. calicopis grown by the Australian national herbarium. photograph by Ron Parsons.
Dendrobium ceraula Heinrich G. Reichenbach named this species in 1876 in Linnaea. The specific epithet refers to the circle formed by the mentum, as ceraula means trumpeter or horn–blower. This species is also known as Dendrobium gonzalesii Quisumbing, but the latter epithet cannot be used, due to the rules of botanical priority meaning that the oldest validly published name has priority. The pendulous pseudobulbs measure up to 1.0 foot (30.5 cm) in length, and new growths will appear from the middle of the stems as well as from the base of the plant. The color range of the blooms is highly variable ranging from white to pink, to pale blue, with deep purple stripes on the labellum. The mentum is tapering and curves around towards the dorsal sepal. This species is endemic to the mountain forests of southern Luzon, where it grows as an epiphyte at elevations of about 3,000 feet (915 m).
[7–11] Various clones of Dendrobium ceraula.
Dendrobium cerinum Heinrich G. Reichenbach named this species in 1879 in the Gardeners’ Chronicle. The specific epithet refers to the waxy appearance of the flowers. This plant is one of the few upright–growing species in the section. The attractive blooms have a waxy appearance with bright, yellow–colored segments and pale purple and green markings in the spur. Some clones have two red blotches on the labellum. This beautiful species is endemic to the Philippines, where it grows as an epiphyte at elevations of about 2,000 feet (610 m).
[12] Den. cerinum
Dendrobium chameleon Oakes Ames named this plant in 1908 in Fascicle II of his Studies in the Family Orchidaceae. The specific epithet is from the Greek chamaileon, referring to the lizard that can change its color, which alludes to the color variation of the flowers. This plant is a pendulous grower and it branches frequently. In the mountains of central Luzon, this species can be found growing close to the ground in fairly shaded locations. The white or pale yellow flowers are variously striped with either green, pink or reddish markings. There are also pure–white forms of this species. Plants of Den. chameleon occur in the Philippines but have also been recorded in southern Taiwan. The plants grow at elevations between 3,000–6,000 feet (915–1829 m).
[13] Den. chameleon
Dendrobium chewiorum Jeffrey J. Wood & Anthony Lamb named this species in 2008 in the Malesian Orchid Journal. The epithet honors Steven and Phillip Chew who were the growers of the type specimen. Stems reach 18 inches (45.7 cm) in length. Inflorescences are to two inches (5.1 cm) long bearing up to four flowers about 1.37 inches (3.5 cm) in diameter by 1.67 inch (4.2 cm) long. This species is only known from Sabah in Borneo, where it grows at elevations of about 1,000 feet (2,540 m).
[14] Dendrobium chewiorum grown by C. Wong and photographed by Ron Parsons.
Dendrobium crassimarginatum Louis O. Williams named this species in 1937 in the Botanical Museum Leaflets, Harvard University. The specific epithet refers to the thickened margins of the labellum. The flowers are highly fragrant and quite large for this section, being about two inches (5.1) across at the widest point. This species is known only from Leyte on the central Philippine archipelago where it grows on the underside of branches in among mosses at elevations of about 2,000 feet (610 m).
[15] Dendrobium crassimarginatum
Dendrobium crocatum Joseph D. Hooker first described this species in 1890 in the Flora of British India. The specific epithet refers to the coloration of the flowers. Stems are long and thin, to 2.0 feet (61 cm) long and can be purple to maroon in color. Inflorescences are about 2.0 inches (5.1 cm) long bearing up to eight flowers about 1.5 inches (3.8 cm) in width by 2.0 inches (5.1 cm) in length. This species is only known from southern Thailand and Peninsular Malaysia where it grows in the lowlands, often close to rivers.
[16] Dendrobium crocatum
Dendrobium cumulatum John Lindley described this species in 1855 in the Gardeners’ Chronicle. The specific epithet refers to the crowded pseudobulbs. The plant reaches 2.0 feet (61 cm) in length. Inflorescences bear up to six flowers about 1.5 (3.8 cm) inches in diameter. This species has been recorded from India, Myanmar, Indochina, and Thailand, where it grows at elevations to 3,000 feet (914 m).
Dendrobium derryi Henry Ridley named this species in 1907 in Materials for a Flora of the Malayan Peninsula. The specific epithet honors a Mr. Derry, collector of the type specimens. Plants can reach 3.0 feet 91 cm) in length. Inflorescences are short and can bear up to six blooms, but usually, it is two to three flowers. The plants have been recorded from Peninsular Malaysia, Sumatra, and Borneo, where it grows at elevations of 1,000–6,000 feet (304–1,829 m).
[17] Dendrobium derryi
Dendrobium diffusum Louis O. Williams named this species in 1937 in the Botanical Museum Leaflets, Harvard university. The specific epithet refers to the widely spreading growth habit of the stems. The plant grows to 2.0 feet (61 cm) long. The inflorescence bears one or two blooms about 1.0 inch (2.5 cm) in diameter. This species is endemic to the Philippines where it is known to occur on the island of Mindoro, as well as northern Mindanao. It grows as an epiphyte at around 2,000 feet (610 m).
[18] Den. diffusum grown and photographed by Derek Cabactulan.
Dendrobium fairchildiae Described by Ames & Quisumbing, this plant is an outstanding and large species, which can be observed growing on rocks in the mountains of central Luzon. However, its usual habitat is on the trunks of trees. The large flowers (1.75 inch [4.4 cm] in diameter) are mostly white with the tips of the segments being pale pink or purplish. An albinistic form of this species has also been described with pure–white flowers with some yellow in the base of the labellum. A prominent feature is the long spur, which is about 1.25 inches (3.2 cm) long, with the final 0.38 inch (1.0 cm) being bent towards the plant. It is only recorded from the mountains of central Luzon and the island of Catanduanes, which is to the east of southern Luzon.
[19] Dendrobium fairchildiae
[20] Dendrobium fairchildiae f. album grown and photographed by March Lomongo.
Dendrobium guerreroi Oakes Ames and Eduardo Quisumbing first named this species in 1932 in the Philippine Journal of Science. The specific epithet honors Dr. Leon Ma. Guerrero, is a specialist in the medicinal plants of the Philippines. I have only seen a few plants of this rare species. Plants reach a length of 18 inches (46 cm). Inflorescences carry up to 15 flowers, about 1.25 inches (3.2 cm) in diameter. This species is endemic to the Philippines where it has been recorded from the island of Mindoro, the island of Dinagat to the north of Mindanao, and several northern provinces of Mindanao. It grows epiphytically at elevations of about 1,600 feet (488 m). The distribution records suggest that it is widely distributed, which raises the possibility of past misidentifications. In any case, little is known about this delightful species.
[21] Dendrobium guerreroi
[22] Dendrobium cumulatum
Dendrobium ionopus Heinrich G. Reichenbach named this species in 1882 in the Gardeners’ Chronicle. The specific epithet refers to the purplish stripes on the leaves and their sheaths. This plant is a medium–sized species with a semi– pendulous habit and the stems reach a length of 2.0 feet (61 cm). Numerous inflorescences can be produced carrying up to twenty flowers each. The blooms are about 0.75 inch (1.9 cm) in diameter. The flower color is highly variable: flowers can be bronze in color, others are pure green, and, recently, a white form has been found in the islands of the central Philippines. This species is endemic to the Philippines and has been found in a number of the provinces of Luzon and the islands of the central archipelago. It grows as an epiphyte at elevations of about 5,000 feet (1524 m).
[23] A white form of Den. ionopus grown and photographed by Raven Schneider.
[24–26] Various clones of Den. ionopus.
Dendrobium jimcootesii Derek Cabactulan and Dr. MiguelDavid De Leon named this plant in 2016 in the German journal Die Orchidee (The Orchid). The specific epithet honors the author of this article. The plants are pendulous growers, branch freely, and reach lengths of 2.0 feet (61 cm). The flowers are about 1.0 inch (2.5 cm) in diameter. It is endemic to the mountains of northern Mindanao in the Philippines. It grows on the mossy trunks and branches of trees at elevations of around 5,000 feet (1524 m) in cloud forests.
Dendrobium kruiense Johannes J. Smith named this orchid in 1926 in Bulletin du Jardin Botanique de Buitenzorg (Bulletin of the Botanic Garden Buitenzorg). The specific epithet refers to the town of Krui in Sumatra, Indonesia. The plants reach 2.0 feet (61 cm) in length. Inflorescences only bear a couple of 1.0–inch (2.5 cm) flowers. It is endemic to the island of Sumatra where it grows as an epiphyte at elevations of around 2,000 feet (610 m).
Dendrobium lampongense Johannes J. Smith named this orchid in 1908 in the Bulletin de Départment de l’Agriculture aux Indies Néerlandaises. Buitenzorg. (Bulletin of the Department of Agriculture in the Netherland Indies. Buitenzorg). The specific epithet refers to the Lampong province of Sumatra in the Indonesian archipelago. The plant can reach more than 2.0 feet (61 cm) in length. Inflorescences can produce up to seven flowers about 2.0 inches (5.1 cm) in diameter. This species has been recorded from Peninsular Malaysia, Thailand, Sumatra and Borneo. It grows as an epiphyte at elevations of between 600–900 feet (183–274 m).
[27] Dendrobium lampongense
[28] Den. jimcootesii grown and photographed by Georg Hampel.
Dendrobium mutabile Carl Blume first named this species in 1825 as Onychium mutabile. John Lindley transferred it to the genus Dendrobium in 1830 in his Genera and Species of Orchidaceous Plants. The specific epithet refers to the variation found within this species. Plants can reach 3.0 feet (91 cm) in length but usually are much shorter. Inflorescences can carry up to fifteen flowers about 1.25 inches (3.2 cm) in diameter. This lovely species in endemic to the islands of Java and Sumatra, Indonesia. It grows at elevations of between 1,600–6,000 feet (488–1829 m). Plants have been found on trees and also rocks.
[29] Dendrobium mutabile
Dendrobium obrienianum Fritz Kraenzlin named this plant in 1892 in the Gardeners’ Chronicle. The specific epithet honors a Mr. O’Brien who may have been the first person to flower this species in Europe. Plants are pendulous and can reach over 3.0 feet (91 cm) in length. Inflorescences are over 8.0 (20.3 cm) inches in length carrying up to twenty well– spaced flowers, which are approximately 0.63 inches (1.6 cm) across the petals. This species occurs in the Maluku Islands (Moluccas) and the Lesser Sunda Islands in Indonesia. Plants in cultivation in Bali, Indonesia, grow and flower at elevations of about 3,300 feet (1,006 m).
[30] Dendrobium obrienianum grown and photographed by Jeff Champion.
[31] Dendrobium obrienianum grown and photographed by Ong Poh Teck.
Dendrobium phillipsii Oakes Ames and Eduardo Quisumbing named this species in 1935 in the Philippine Journal of Science. The specific epithet honors Mr. L.H. Phillips, collector of the specimens used to make the description. This orchid is the sister species of Den. fairchildiae and is relatively smaller with pseudobulbs measuring about 2.0 feet (61 cm) long. The flower color is predominantly white, while the spur and the throat of the labellum are yellow. The final portion of the spur points downwards towards the ground, which is one of the distinguishing features that separates this species from Den. fairchildiae. Dendrobium phillipsii is endemic to the Philippines and is only known from northern Mindanao at elevations of about 3,000 feet (914 m), where it grows as an epiphyte.
[32] Dendrobium phillipsii
Dendrobium profusum Heinrich G. Reichenbach described this species in 1884 in the Gardeners’ Chronicle. The specific epithet refers to the profuse flowering habit of this orchid. The stems reach about 2.0 (61 cm) feet in length. Inflorescences can bear up to 15 flowers about 1.0 inch (2.5 cm) in diameter. Without a doubt, this is one of the most delightfully colored members of this section. The sepals and petals are cream to yellow, marked to varying degrees with pink–to–purple spots or blotches. This species is endemic to the largest island of the Philippines, Luzon. It grows in the lowland forests as an epiphyte at elevations up to 1,000 feet (305 m). It enjoys brightly lit positions.
[33–35] Three different color forms of Dendrobium profusum.
[36] Dendrobium profusum ‘Purple Haze’
[37] A green form of Dendrobium profusum grown and photographed by Ronny Boos.
Dendrobium ravanii The author of this article described this species in 2008 in the German Orchideen Journal. The specific epithet honors the discoverer of this orchid, Mr. Ravan Schneider. It is a most beautiful addition to the Philippine orchid flora. The plants are semi–pendulous and can reach lengths of almost 18 inches (46 cm). Flowers are usually white in color, but pink forms have also been seen, and the blooms are about 1.25 inches (3.2 cm) wide. The markings on the labellum, which are purplish, vary considerably in their intensity. The plants are only found in the mountains of northern Mindoro in shaded locations at elevations of between 1,800– 2,500 feet (550–762 m). Dendrobium ravanii is probably the smallest–growing member of the section, and plants a mere 4.0 inches (10.2 cm) long have flowered in my collection.
[38] Dendrobium ravenii
[39] Den. ravenii ‘Pink Back’
Dendrobium sanguinolentum John Lindley named this glorious species in 1842 in Edwards’s Botanical Register. The specific epithet refers to the purple–stained leaves, and the tips of the floral segments of some forms of this species. The plants can reach over 3.0 feet (91 cm) in length. Inflorescences are short and can have up to nine but more usually about four flowers, which are about 1.25 inches (3.2 cm) in diameter. There are two color forms of this orchid: one in which the flowers are a plain, deep cream to pale orange, and the other on which there are purplish red tips to the floral segments. This orchid has been recorded from Thailand, Peninsular Malaysia, Indonesia and Borneo. It grows as an epiphyte at elevations form sea level up to about 2,000 feet (610 m).
[40–41] Dendrobium sanguinolentum
Dendrobium serena–alexianum Jeffrey J. Wood and Anthony Lamb named this species in 2008 in the Malesian Orchid Journal. The specific epithet honors Serena and Alexander Lamb, children of the second author. Plants can reach 3.0 feet (91 cm) in length. Inflorescences carry up to eight flowers about 1.25 inches (3.2 cm) in diameter by about 1.5 inches (3.8 cm) long. This species is only known from the foothills (700–4,000 feet [213–1219 m]) of Mount Kinabalu in Sabah, Borneo.
[42–43] Dendrobium serena–alexianum grown by Cindy Hill. Photograph by Ron Parsons
Dendrobium serratilabium Louis O. Williams named this plant in 1937 Botanical Museum Leaflets, Harvard university. It has a labellum, which has beautifully serrated edges, thus the specific epithet. The plant branches considerably with new growths appearing from both the base of the plant and from along the pseudobulbs. Flower color is variable, commonly cream with different degrees of red stripes on the segments, while others are orange–yellow and lack the red stripes. Clones also exist without any striping. This is a fairly widespread species throughout the Philippines, preferring shady locations in mountain forests at elevations over 3,000 feet (914 m).
[44] Dendrobium serratilabium grown and photographed by Georg Hampel.
[45–47] Various color forms of Dendrobium serratilabium.
Dendrobium victoriae–reginae Augustus Loher named this wonderful species in 1897 in the Gardeners’ Chronicle. The specific epithet honors Queen Victoria, who was about to celebrate her sixtieth anniversary on the British throne. This species is probably the most well–known and widely grown species from this section. The huge variation in the color of the flowers is a joy to behold. The most popular and desirable forms are those where the flowers are of dark–blue shades. Inflorescences are short and can carry up to three blooms about 1.5 inches (3.8 cm) wide. As this species occurs in the high moist mountains (over 4,000 feet [1219 m]) of the Philippines, it can be successfully cultivated in a shade house in temperate zones and can withstand winter minimum temperatures of 50 F (10 C). Plants are best kept in lightly shaded positions with constant air movement and should not be allowed to dry out. This wonderful species is endemic to the Philippines, and it occurs throughout the archipelago.
[48–54] Various color forms of Dendrobium victoriae–reginae.
[55] Dendrobium victoriae–reginae grown and photographed by Rey Abellada.
[56] Dendrobium victoriae–reginae f. album grown and photographed by Kobe Felicia.
[57] A very well–flowered, richly colored form of Dendrobium victoriae–reginae.
Dendrobium yeageri Oakes Ames & Eduardo Quisumbing named this species in 1933 the Philippine Journal of Science. The specific epithet honors Dr. C.H. Yeager who was with the group that discovered the first specimens described. This is a medium– sized plant with pendulous pseudobulbs measuring up to 18 inches (45.7 cm). The attractive flowers are colored pale purple with darker stripes, while the tip of the labellum is white, and are about 1.25 inches (3.2 cm) in diameter. This is another plant that tolerates cooler conditions as it comes from the mountains of Luzon in the Philippines. It should be noted that Den. yeageri, Den. ceraula and Den. victoriae–reginae are all closely related species and appear to have a common ancestor.
[58–59] Two different forms of Dendrobium yeageri.
CULTURE
A number of the species in section Calcarifera are plants of the tropical lowland rainforests and, as a rule, they require moderately bright, moist and humid conditions in cultivation with warm–to–intermediate temperatures (minimum 61 F [16 C]) throughout the year. For those species which come from high–altitude areas, such as Den. victoriae–reginae, cooler temperatures (range 77 F [25 C] maximum, 50 F [10 C] minimum) are desirable. In temperate climates, successful cultivation can be achieved in a glasshouse with appropriately controlled growing conditions. We grow plants in either pots or on mounts of treefern fiber. For pots, a well–draining epiphyte medium should be used, consisting of pine bark mixed with pebbles or perlite. When plants are grown on mounts, sphagnum moss may be used to hold a little moisture around the roots. Bright filtered light is important, as is good air movement to reduce fungus–induced rot. Plants must not dry out, and it is recommended that they receive copious watering and regular applications of weak fertilizer solution during the growing period. In general, watering and fertilizing should be eased during the cooler months.
The plants described here are relatively easy to care for and deserve to be more widely cultivated, although some species are uncommon and may not be easily available. Most have a pendulous growth habit requiring only small or confined spaces, and well–grown specimens will reward the proud owner with regular flushes of highly attractive flowers.
Acknowledgments
Thanks to the following friends for allowing me the use of their images to enhance this article: Rey Abellada (the Philippines), Ronny Boos (the Philippines), Derek Cabactulan (the Philippines), Jeffrey Champion (Bali, Indonesia), Kobe Felicia (the Philippines), Dr. Nelson Geraldino (the Philippines), Georg Hampel (Germany), March Lomongo (the Philippines), Ron Parsons (uSA), Ravan Schneider (Germany), and Ong Poh Teck (Malaysia).
References
Comber J.B. 2001. Orchids of Sumatra. Natural History Publications (Borneo), Sabah, Malaysia.
Cootes J. 2011. Philippine Native Orchid Species. Katha Publishing, Philippines.
Ong P.T. and D. Metusala. 2023. Dendrobium obrienianum Kraenzl. (Section Pedilonum) – Reintroduction of an Old Taxon in Cultivation. Malesian Orchid Journal. 26.
Seidenfaden G. and J.J. Wood. 1992. The Orchids of Peninsular Malaysia and Singapore. Olsen & Olsen, Fredensborg.
Wood H.P. 2006. The Dendrobiums. A.R.G. Gantner Verlag, Ruggell/Liechtenstein.
Wood J.J. and A. Lamb. 2008. Two New Species of Dendrobium (Section Calcarifera) from Sabah. Malesian Orchid Journal. 2.
