Dendrobium Species Culture

Dendrobium Species Culture

This article was provided by Charles and Margaret Baker.
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Note: These articles are part of the Orchid Species Culture series of books and articles. This part was originally printed November 1996 in Orchids 65(11):1190-1195.

DENDROBIUM SPECIES CULTURE

Part 1 - Dendrobium nobile

Charles and Margaret Baker

Dendrobium nobile, Dendrobium phalaenopsis, and Dendrobium bigibbum are three popularly grown Dendrobium species which have been used extensively in hybridizing. These species and their hybrids are often added to collections without the grower being aware of their very different cultural requirements. We hope that a knowledge of the climatic conditions in the three habitats will help growers decide whether they can provide the conditions needed to grow and bloom these species and many of their hybrids.

Dendrobium species originate over an extremely large area with a wide range of habitat elevations. It is, therefore, impossible to accurately make any generalizations about their culture. Often heard remarks such as, "Dendrobium species are difficult to grow", "Dendrobiums won't grow in this area", or "Beginners should avoid Dendrobium species" are simply generalizations that are too broad to be accurate. It is true that individual species often require very specific growing conditions, but with approximately 1240 species to choose from, plants can generally be found that are suitable for practically any growing area.

A few general facts about the large and varied genus Dendrobium might help growers understand the difficulty in trying to apply generalizations to so many species. Dendrobium habitat extends from India in the west, to Japan in the north, Australia and New Zealand in the South, and ranges eastward to include most of the Pacific Islands. Within this huge region, Dendrobium species are found from sea level to about 12,000 feet (3660 m).

Because of the conditions in our growing area, we are particularly fond of plants from the mountain regions of India across Southeast Asia into southwestern China. These plants usually require a cool, dry winter rest, which means that a minimum of care and heat is required during winter. Consequently the growers are able to enjoy a winter rest along with the plants. Some of the popularly grown Dendrobiums from this region are from a group of closely related plants that are sometimes referred to as the 'soft cane' species or 'nobile-type' dendrobiums. Species in this group are typified, as one might suspect, by Dendrobium nobile. They tend to have rather large, attractive flowers and are generally relatively easy to cultivate. Dendrobium nobile is one of the most frequently grown Dendrobium species, but other species from the region that require similar growing conditions include D. aphyllum, D. bensoniae, D. christyanum, D. crepidatum, D. devonianum, D. draconis, D. falconeri, D. farmeri, D. fimbriatum, D. lindleyi, D. loddigesii, D. ochreatum, D. parishii, D. trigonopus, D. unicum, and D. wardianum.

The three Dendrobium to be discussed in this article have been the most widely used in hybridizing. Because hybrids often require conditions similar to those needed by the parents, understanding the culture of the parents may help grow the offspring.

D. nobile was once used extensively in hybridizing with 77 hybrids registered in which it was a parent. The most commonly used parents in recent registrations, however, have been the Australian species D. phalaenopsis and the closely related D. bigibbum.

Cultivation of each of these species is relatively easy once the grower has an understanding of the conditions found in the respective habitats. The following information has been extracted, with slight modifications, from the forthcoming book Orchid Species Culture - Dendrobium, which is being published by Timber Press. Cultural recommendations for D. bigibbum and D. phalaenopsis will be included in later issues.

Dendrobium nobile Lindley

AKA: D. coerulescens Wallich, D. formosanum (Rchb. f.) Masamune, D. lindleyanum Griffith. The name D. friedericksianum is sometimes used for plants which are actually D. nobile. D. nobile var. pallidiflora Hooker is considered a synonym of D. primulinum Lindley.

ORIGIN/HABITAT: Southeast Asia, including Nepal, Sikkim, Bhutan, northeastern India, Burma, Thailand, Laos, Vietnam, and much of southern China. In India, plants grow at 650-6550 ft. (200-2000 m). They are widespread in northern Thailand at 1950-4900 ft. (600-1500 m).

CLIMATE: Station #48327, Chiang Mai, Thailand, Lat. 18.8N, Long. 99.0E, at 1100 ft. (335 m). Temperatures are calculated for an elevation of 3500 ft. (1070 m), resulting in probable extremes of 101F (38C) and 30F (-1C).

N/HEMISPHERE    JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC
F AVG MAX        77   82   87   88   86   82   81   79   80   81   78   76
F AVG MIN        48   49   54   62   66   66   66   67   65   63   58   49
DIURNAL RANGE    29   33   33   26   20   16   15   12   15   18   20   27
RAIN/INCHES     0.3  0.4  0.6  2.0  5.5  6.1  7.4  8.7 11.5  4.9  1.5  0.4
HUMIDITY/%       73   65   58   62   73   78   80   83   83   81   79   76
BLOOM SEASON     **  ***  ***  ***   **    *    *    *    *    *    *    *
DAYS CLR @ 7AM    5    5    2    2    1    0    0    0    0    1    3    3
DAYS CLR @ 1PM    9    8    4    2    0    0    0    0    0    0    1    3
RAIN/MM           8   10   15   51  140  155  188  221  292  124   38   10
C AVG MAX      25.0 27.8 30.6 31.2 30.0 27.8 27.3 26.2 26.7 27.3 25.6 24.5
C AVG MIN       8.9  9.5 12.3 16.7 18.9 18.9 18.9 19.5 18.4 17.3 14.5  9.5
DIURNAL RANGE  16.1 18.3 18.3 14.5 11.1  8.9  8.4  6.7  8.3 10.0 11.1 15.0
S/HEMISPHERE    JUL  AUG  SEP  OCT  NOV  DEC  JAN  FEB  MAR  APR  MAY  JUN

Cultural Recommendations

LIGHT: 3500-4500 fc. The heavy summer cloud cover indicates that some shading is needed from spring through autumn, but light should be as high as the plant can tolerate, short of burning the leaves. Growers report that D. nobile tolerates full sun when grown outdoors if acclimated early in spring and if air movement is excellent. Growers indicate that light is high enough when leaves are slightly yellow.

TEMPERATURES: Summer days average 79-82F (26-28C), and nights average 66-67F (19-20C), with a diurnal range of 12-16F (7-9C). Spring is the warmest time of the year. Days average 86-88F (30- 31C), and nights average 54-66F (12-19C), with a diurnal range of 20-33F (11-18C). Growers indicate that plants do well outdoors providing night temperatures are near 50F (10C).

HUMIDITY: Near 80% in summer, dropping to near 60% in winter.

WATER: Rainfall is moderate to heavy from late spring through early autumn, but conditions are much drier in winter. Cultivated plants should be kept moist while actively growing, but water should be gradually reduced after new growths mature in autumn.

FERTILIZER: 1/2 to full strength, applied weekly while plants are actively growing. A high-nitrogen fertilizer is beneficial from spring to midsummer, but a fertilizer high in phosphates should be used in late summer and autumn. W. Neptune, in his 1984 American Orchid Society Bulletin article, reported that he obtains better flowering, more uniform growth, and a minimum of keikis by using a 10-30-20 fertilizer mixed at 1 tsp. per gal. (1.3 ml per liter) once a week from spring through midsummer. In late summer and autumn, he switches to a 0-44-0 fertilizer mixed at the same dilution rate. Water and fertilizer are then withheld through winter until the following spring.

REST PERIOD: Winter days average 76-82F (25-28C), and nights average 48-49F (9-10C), with a diurnal range of 27-33F (15-18C). Overnight lows are below 50F (10C) for 3 months. Plants should be able to tolerate temperatures a few degrees below freezing for short periods, but such extremes should be avoided in cultivation. During very cold weather, a plant's chance of surviving with minimal damage is better if it is dry when temperatures are low. Growers report that the plants from this habitat do tolerate light frost. In the habitat, rainfall averages are very low for 4-5 months in winter, but during the early part of the season the high relative humidity indicates that additional moisture is available from frequent fog, mist and heavy deposits of dew. Growers sometimes recommend eliminating water in winter, but plants are healthiest if for most of the winter they are allowed to become somewhat dry between waterings but do not remain dry for extended periods. For 1-2 months in late winter, however, conditions are clear, warm, and dry with humidity so low that even the moisture from morning dew is uncommon. Plants should be allowed to dry out completely between waterings and remain dry longer during this time. Occasional early morning mistings between waterings may help keep the plants from becoming too dry. Fertilizer should be greatly reduced or eliminated until water is increased in spring. A cool, dry rest is essential for cultivated plants and should be continued until new growth starts in spring. In the habitat, light is highest in winter.

GROWING MEDIA: Plants may be mounted on cork or tree-fern slabs if humidity is high and plants are watered at least once daily in summer. Large plants are best potted in an open, fast draining media. Growers indicate that the type of medium is not critical but that using an undersized clay pot, which is barely large enough to hold the roots and allow room for 2 year's growth, is very important. Repotting should be avoided until the medium starts to break down. When necessary, repotting is best done when new root growth starts or as soon after flowering as possible.

MISCELLANEOUS NOTES: The bloom season shown in the climate table is based on cultivation records. Although considered difficult by many growers, D. nobile is one of the most commonly cultivated Dendrobium species. It flowers profusely if fertilized regularly while growing and given a cool, dry rest with high light to initiate blooms. A single specimen plant was reported to have produced more than 1000 flowers at one blooming. Bloom time may be delayed by maintaining cool, dry conditions and low light until close to the time the blooms are wanted. Growers without greenhouses grow D. nobile outdoors in spring and summer and bring it indoors in autumn. This suggests that high winter light is not critical. Plants may be propagated vegetatively by potting keikis that develop at nodes on old canes. Also, old canes may be cut into 8- 10 in. (20-25 cm) sections and placed on damp sphagnum. These sections of old canes will sometimes produce keikis that may then be potted when they start to grow roots. Collected stems are dried and used in Chinese medicine.

Plant and Flower Information

PLANT SIZE AND TYPE: A 24-35 in. (60-90 cm) sympodial epiphyte.

PSEUDOBULB: 24-35 in. (60-90 cm) long. The stems are swollen at the apex and taper to a narrower base. They are clustered on a short connecting rhizome. The canes are often yellowish, somewhat zigzag, round in cross-section, and become furrowed with age. The nodes are usually thickened and flattened.

LEAVES: 6-7. The leaves are distichous, 3-4 in. (7-10 cm) long, oblong to strap-shaped, softly leathery, and deciduous after 2 years.

INFLORESCENCE: Short. Many inflorescences emerge simultaneously from the upper nodes of both leafy and older leafless canes.

FLOWERS: 1-4 per inflorescence. The blossoms, which are 2.4-4.0 in. (6-10 cm) across, have a waxy and heavy texture. The oval sepals and much wider, wavy-margined petals are normally white with rose tips. The downy lip, which is tubular at the base, is cream-white with rose at the apex and has deep crimson or crimson-purple markings in the throat. It is occasionally pure white. The flowers are highly variable, however, with even pure white blossoms occurring occasionally. The many horticultural variants are based primarily on differences in color. The very fragrant blossoms last 3-6 weeks, or longer if conditions are cool and light is low. Recognized varieties include var. formosanum Rchb. f., var. nobilis Burbidge, and var. pallidiflorum Hooker.

HYBRIDIZING NOTES: Chromosome counts are n = 19, n = about 20, 2n = 38, 2n = 40, 2n = 57. When tested as D. nobile var. nobile the counts were 2n = 19, 2n = 38, and 2n = 57. D. nobile var. cooksonianum produced counts of n = 19 and 2n = 38, and D. nobile var. nobilius had counts of n = 19, 2n = about 57. D. nobile var. pendulum 2n = 38, D. nobile var. sanderianum was 2n = 38-40 , D. nobile var. virginale was 2n = 57. D. nobile var. wallichianum was 2n = 38, D. nobile 'King George' was n = 38 and 2n = 76 . D. formosanum had a count of 2n = 38. D. nobile 'Sir F. Moore' had twice the normal count at 2n = 76. Seeds are ready for green-pod culture in 150-180 days. They are easy to maintain in flask. D. nobile has been widely used in hybridization, and offspring usually have numerous flowers with the size and thick texture of the D. nobile parent. D. nobile is known to hybridize naturally with D. primulinum Lindley producing D. X pitcheranum Rchb. f.

REFERENCES:

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Bechtel, H., P. Cribb, and E. Launert. 1980. Manual of cultivated orchid species. MIT Press, Cambridge, Mass.

Bhattacharjee, S. 1976. India: Major Dendrobium habitat of the world. American Orchid Society Bulletin 45(8):713.

Bose, T., and S. Bhattacharjee. 1980. Orchids of India. Naya Prokash, Calcutta, India.

Chen, Sing-Chi, and T. Tang. 1982. A general review of the orchid flora of China. Orchid biology: reviews and perspectives vol. II. Ed. by J. Arditti. Comstock Publishing, Cornell University Press, Ithaca, N. Y.

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Hooker, J. 1890-1894. Flora of British India vol. V and VI. L. Reeve & Co., London.

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Kennedy, G. 1975. Dendrobiums of the Sikkim Himalaya and the Burmese-India border. American Orchid Society Bulletin 44(9):797.

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Pridgeon, A., ed. 1992. The illustrated encyclopedia of orchids. Timber Press, Portland, OR.

Rao, A. 1986. Orchid flora of Arunachal Pradesh--a conspectus, in Biology, conservation, and culture of orchids, ed. by S. P. Vij. The Orchid Society of India. Affiliated East-West Press Private Ltd. New Delhi, India.

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Schelpe, S., and J. Stewart. 1990. Dendrobiums-an introduction to the species in cultivation. Orchid Sundries, Ltd., New Gate Farm, Stour Provost, Gillingham, Dorset SB8 5LT, Great Britain.

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Seidenfaden, G. 1975. Contributions to a revision of the orchid flora of Cambodia, Laos, and Vietnam. Kai Olsen, 10 Helstedsvej, DK-3480, Fredensborg, Denmark.

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Note: These articles are part of the Orchid Species Culture series of books and articles. This part was originally printed December 1996 in Orchids 65(12): 1309-1313.

DENDROBIUM SPECIES CULTURE

Part 2 - Dendrobium phalaenopsis

Charles and Margaret Baker

Northeastern Australia is home to a group of orchids that are among the most beautiful found anywhere. As mentioned in the article on Dendrobium nobile in a previous Bulletin, D. phalaenopsis has in recent times become the most widely used Dendrobium species in hybridization. Over the years there have been 266 hybrids registered with D. phalaenopsis as one of the parents, with most of the activity occurring after 1960. In addition, the closely related D. bigibbum has been registered in 127 crosses during the same period.

There is a great deal of confusion surrounding these species, and it will probably continue to be with us for some time. Although these two species have been lumped together at times and are still considered to be synonymous by some authorities, the most recent taxonomic work has them listed as separate species. While very similar to each other, the flowers of D. bigibbum tend to be somewhat smaller, have sepals and petals that are more strongly reflexed, and a lip that is broader and more rounded or notched at its apex. In addition, plants known as D. bigibbum are found in areas nearer the equator and, therefore, require much warmer temperatures, especially during winter.

We suspect that many of the cultural problems encountered when attempting to grow these plants are rooted in confusion resulting from misidentification and mislabeling. For example, the first Dendrobium plant we got for our collection was an alba form of D. phalaenopsis. Our greenhouse conditions are such that if we place this plant in the warmest area, conditions are only slightly too cool for plants of this species and it blooms well almost every year. With this success, we picked up a companion plant, one with dark purple flowers, that was also labeled D. phalaenopsis. Even though placed next to the original plant, this second one has never bloomed. It does try every 2-3 years, but the few buds that develop on the short, puny spikes soon turn yellow and fall off. We have been unable to determine the precise reason or reasons for this failure. We at first concluded that the purple flowered plant probably required higher light in autumn and winter than we are able to provide in this area. More recently, we are wondering if this second plant is not actually a D. bigibbum which needs temperatures about 10F (6C) warmer than we are providing. In fact, the average night temperature during winter in our greenhouse is slightly cooler than the record lows in the D. bigibbum habitat.

To hopefully help clear up some of the confusion surrounding these beautiful Australian species and assist growers in better understanding their cultural requirements, the section for D. phaleanopsis has been extracted from our forthcoming Timber Press book and, with minor changes, is presented here. The section covering D. bigibbum will be presented in a later issue.

Dendrobium phalaenopsis Fitzgerald

AKA: Normally considered synonymous with or a variety of D. bigibbum Lindley, Clements (1989) includes both D. phalaenopsis and D. bigibbum as separate species. He includes D. bigibbum var. macranthum F. M. Bailey, D. bigibbum var. phalaenopsis (Fitzgerald) F. M. Bailey, and D. bigibbum var. superbum hort. ex Rchb. F. as synonyms of D. phalaenopsis Fitzgerald. Clements considers D. phalaenopsis Fitzgerald var. compactum C. White to be a synonym of D. lithocola D. Jones and M. Clements and D. phalaenopsis Fitzgerald var. statterainum hort. ex Sander to be a synonym of D. bigibbum. The plants known as D. phalaenopsis from the islands off West Irian he refers to D. striaenopsis M. Clements and D. Jones. The International Orchid Commission (1993) lists D. schroederianum as a synonym and registers hybrids under the name D. phalaenopsis.

ORIGIN/HABITAT: Northeast Australia. Plants grow on the Cape York Peninsula in the coastal ranges between Mt. Malloy and the Iron Range. Plants grow in very bright conditions on small trees and rocks in fairly open forests. They are normally found in semiarid regions below 2000 ft. (610 m).

CLIMATE: Station #94283, Cooktown, Australia, Lat. 15.5S, Long. 145.2E, at 24 ft. (7 m). Temperatures are calculated for an elevation of 1000 ft. (305 m), resulting in probable extremes of 101F (39C) and 43F (6C).

N/HEMISPHERE    JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC
F AVG MAX        76   77   79   82   85   86   86   85   83   82   79   77
F AVG MIN        63   64   67   70   72   72   72   72   72   70   67   65
DIURNAL RANGE    13   13   12   12   13   14   14   13   11   12   12   12
RAIN/INCHES     0.9  1.2  0.6  1.0  2.5  6.6 14.4 13.7 15.3  8.8  2.8  2.0
HUMIDITY/%       73   69   68   67   68   71   75   76   77   75   74   75
BLOOM SEASON      *                             *    *    *    *    *    *
DAYS CLR        N/A
RAIN/MM          23   30   15   25   64  168  366  348  389  224   71   51
C AVG MAX      24.3 24.9 26.0 27.7 29.3 29.9 29.9 29.3 28.2 27.7 26.0 24.9
C AVG MIN      17.1 17.7 19.3 21.0 22.1 22.1 22.1 22.1 22.1 21.0 19.3 18.2
DIURNAL RANGE   7.2  7.2  6.7  6.7  7.2  7.8  7.8  7.2  6.1  6.7  6.7  6.7
S/HEMISPHERE    JUL  AUG  SEP  OCT  NOV  DEC  JAN  FEB  MAR  APR  MAY  JUN

Cultural Recommendations

LIGHT: 3000-4500 fc. Seasonal light variation is minor at this latitude, but in the habitat, winter light is higher because weather is often clear. For cultivated plants, high light and strong air movement are vitally important year-round.

TEMPERATURES: Summer days average 85-86F (29-30C), and nights average 72F (22C), with a diurnal range of 13-14F (7-8C). The diurnal range varies only 3F (2C) all year.

HUMIDITY: Near 70-75% most of the year, dropping to 65-70% in late winter and spring.

WATER: Rainfall is moderate to heavy during summer and early autumn, but conditions are much drier in winter. Cultivated plants should be kept moist while actively growing, but water should be gradually reduced in autumn. Australian growers recommend a daily morning misting in summer, even for pot-grown plants, with evening mistings also given when temperatures are above 91F (33C).

FERTILIZER: 1/4-1/2 recommended strength, applied weekly. A high nitrogen fertilizer is beneficial from spring to midsummer, while a fertilizer high in phosphates should be used in late summer and autumn.

REST PERIOD: Winter days average 76-79F (24-26C), and nights average 63-67F (17-19C), with a diurnal range of 12-13F (7C). For 4 months in winter and spring, rainfall is low. The low humidity indicates that even moisture from dew is uncommon. In cultivation, the dry rest should be started after flowering. Plants should be allowed to dry out between waterings, but they should not remain completely dry for extend periods because they are very slow to recover if allowed to shrivel. Occasional early morning mistings between waterings may help keep plants from becoming too dry. After new growth is evident in spring, water should be gradually increased. Because new growths are very susceptible to infection and rot, care must be taken to keep water off them until they are 2-3 in. (5-8 cm) tall. Fertilizer should be eliminated or greatly reduced until watering is increased in spring. In the habitat, light is highest in winter, so as much light as possible, short of burning the foliage, should be provided for cultivated plants.

GROWING MEDIA: Plants may be mounted on tree-fern or cork slabs if humidity is high and plants are watered at least daily in summer. Several waterings a day may be necessary during particularly hot, dry periods. When plants are potted, excellent drainage in necessary, so a very open and fast draining medium, such as medium cork nuggets or fir bark, should be used. Plants tend to be top heavy, so heavier clay pots are usually preferred. A pot that appears to be too small for the plant usually produces better results. Staking the plant helps support new canes. Repotting is best done when flowering is completed or just as new growth starts in late winter or early spring.

MISCELLANEOUS NOTES: The bloom season shown in the climate table is based on records from the habitat. Cultivation records indicate heaviest blooming in autumn. Growers report that plants do poorly in areas with low winter light and that insufficient light causes buds to drop. D. phalaenopsis is often considered difficult to grow and bloom because it requires high light, warm winter temperatures, and a winter dry season, a combination that is sometimes difficult to provide in a general collection.

Plant and Flower Information

PLANT SIZE AND TYPE: A slender, 16-48 in. (40-122 cm) sympodial epiphyte or lithophyte that is very similar to D. bigibbum. Plants seldom develop into specimen plants as they are very prone to die-back.

PSEUDOBULB: 16-48 in. (40-122 cm) long. The cylindrical stems are slightly swollen at the base. The apical 30% of the stem is leafy. Stems that die back at the base may produce new plants near the apex.

LEAVES: 3-5, rarely as many as 12. The oblong-lanceolate leaves are 3-6 in. (8-15 cm) long. They are leathery, rigid, and flushed with red or purple. Leaves last for 2 years.

INFLORESCENCE: 8-16 in. (20-40 cm) long. Each year, over a period of several years, each growth produces 1-4 inflorescences from nodes near the apex of the pseudobulb. Flowering may continue even after stems are leafless. The inflorescences are usually arching or horizontal, but they may be pendent. Flowers are nicely spaced along the upper half of the raceme.

FLOWERS: 3-20 per inflorescence The showy flowers are 1.4-2.8 in. (3.5-7.0 cm) across with broad overlapping sepals and petals and a heavy texture. They are similar to D. bigibbum, but D. phalaenopsis blossoms are slightly larger with sepals and petals that are recurved only slightly and a lip midlobe that is usually longer and pointed instead of more or less rounded. Flowers are normally deep-lilac, but they may be white, pale lilac, magenta, or purple. All colors are bright and rich. The lip is usually a darker shade of the same color as the sepals and petals with deeper color in the throat and stripes on the oblong, pointed midlobe. The sidelobes are arching. The spur is broad. Blossoms are highly variable in size and color. If they do not become water spotted, flowers last for months, so that plants are in nearly continuous bloom.

HYBRIDIZING NOTES: Chromosome counts are n = 19 and 2n = 38 as D. phalaenopsis Fitzgerald and D. bigibbum Lindley var. superbum hort. Named clones of D. phalaenopsis had variable counts including n = 19, n = 38, and n = variable, 2n = 38, 2n = 76, 2n = about 76, and 2n = 76±1. Johansen indicates that the seeds produced when D. phalaenopsis was self-pollinated contained no visible embryos and no seeds germinated. Capsules opened 197 days after pollination. Seeds are sufficiently mature for green-pod sowing in 120-140 days.

REFERENCES:

Adnams, T. 1981. Selected dendrobiums. The Orchid Review 89(7):205-207, 237-239.

Backer, C., and R. Bakhuizen Van Den Brink. 1968. Flora of Java, vol. III. Wolters-Noordhoff N. V., Groningen, The Netherlands.

Bechtel, H., P. Cribb, and E. Launert. 1980. Manual of cultivated orchid species. MIT Press, Cambridge, Mass.

Bishop, D. 1974. Dendrobium phalaenopsis culture. American Orchid Society Bulletin 43(8):709.

Blake, S. 1962. Dendrobium bigibbum, Dendrobium phalaenopsis and the Cooktown orchid. Proceedings of the Royal Society of Queensland issued 1964. LXXIV:29-44.

Clements, M. 1989. Catalogue of Australian Orchidaceae. Australian Orchid Research vol. 1. D. Jones, ed. Australian Orchid Foundation, 107 Roberts St., Essendon 3040, Victoria, Australia.

Clemesha, S. 1980. Dendrobium bigibbum Lindl. and Dendrobium phalaenopsis R. D. Fitzg. American Orchid Society Bulletin 49(9):991.

Dockrill, A. 1969. Australian indigenous orchids. Society for Growing Australian Plants, Halstead Press, Sydney, Australia.

Ducharme, B. 1974. A novice's experience with Dendrobium phalaenopsis. American Orchid Society Bulletin 43(8):679.

Fennell, T., III. 1986. Evergreen Dendrobium culture - a practical guide for the beginner. American Orchid Society Bulletin 55(11):1109.

Goldblatt, P. 1984. Index to plant chromosome numbers. 1979-1981. Monographs in Systematic Botany from the Missouri Botanical Garden 8.

Goldblatt, P. and D. Johnson, eds. 1990. Index to plant chromosome numbers. 1986-1987. Monographs in Systematic Botany from the Missouri Botanical Garden 30.

Hagar, G. 1979. Dendrobium phalaenopsis -- the "Cooktown orchid". American Orchid Society Bulletin 48(10):1034.

Hamilton, R. 1990. Flowering months of orchid species under cultivation. Orchid Biology Reviews and Perspectives vol. 5. J. Arditti, ed. Timber Press, Portland, Or.

Hashimoto, K. 1981. Chromosome count in Dendrobium 1. 87 species. Bulletin of the Hiroshima Botanical Garden 4:63-80.

Hashimoto, K. 1987. Karyomorphological studies of some 80 taxa of Dendrobium, Orchidaceae. Bulletin of the Hiroshima Botanical Garden 9:1-5.

Hawkes, A. [1965] 1987. Encyclopaedia of cultivated orchids. Faber and Faber, London.

Heeseler, R. 1987. Orchid species culture guide. Richard C. Heeseler, P. O. Box 1525, Seaford, N. Y., U. S. A. 11783.

Holttum, R. 1964. A revised flora of Malaya. Vol. 1, orchids. Government Printing Office, Singapore.

Index Kewensis. [1895] 1977. Vol. I-II ( -1885). An enumeration of the genera and species of flowering plants. Oxford University Press, Amen House, London E. C. 4. Reprint by Otto Koeltz Science Publishers, D-6240 Koenigstein/West Germany.

International Orchid Commission. 1993. Handbook on orchid nomenclature and registration. 4th ed., rev. International Orchid Commission, London.

Johansen, B. 1990. Incompatibility in Dendrobium (Orchidaceae). Botanical Journal of the Linnean Society 103:165-196 with 10 figures.

Kränzlin, F. [1910] 1957. Orchidaceae-Monandrae-Dendrobiinae. In Das Pflanzenreich. Regni vegetabilis conspectus, ed. by A. Engler. Reprinted Im Verlag von H. R. Engelmann (J. Cramer). Weinheim/Bergstr.

Light, M. 1990. Doing your part for conservation--1. Getting seeds. American Orchid Society Bulletin 59(8):787.

Miyamoto, C. 1988. Hawaiian achievements with Dendrobium phalaenopsis. Orchid Digest 52(3):101.

Northen, R. 1970. Home orchid growing. Van Nostrand Reinhold, New York.

Ossian, C. 1992. Dendrobium culture: part 2 care and feeding of the sections Phalaenanthe and Spatulata. Orchid Digest 56(3):117.

Peterson, R. 1976. Dendrobium hybrids -- Hawaii's endemic orchids. American Orchid Society Bulletin 45(3):235.

Rentoul, J. 1982. Growing orchids, book 3. Vandas, dendrobiums and others. Timber Press, Portland, OR.

Rittershausen, W. 1991. Dendrobium phalaenopsis and its hybrids. The Orchid Review 99(10):310-316.

Rupp, H., and T. Hunt. 1947. A review of the genus Dendrobium (Orchidaceae) in Australia. The Proceedings of the Linnean Society of New South Wales vol. LXXII: 233-251.

Sauleda, R. 1976. Harvesting times of orchid seed capsules for the green pod culture process. American Orchid Society Bulletin 45(4):305-309.

Schelpe, S., and J. Stewart. 1990. Dendrobiums-an introduction to the species in cultivation. Orchid Sundries, Ltd., New Gate Farm, Stour Provost, Gillingham, Dorset SB8 5LT, Great Britain.

Schuster, C. [1931-1943] 1981. Orchidacearum iconum index. Feddes Repertorium specierum novarum regni vegetabilis Beiheft 60. Reprinted by Otto Koeltz Science Publishers, D-634 Koenigstein, Germany.

Shuttleworth, H., H. Zim, and G. Dillon. 1970. Orchids, a golden guide. Golden Press, New York.

Tanaka, R., and H. Kamemoto. 1984. Chromosomes in orchids: counting and numbers. Appendix in Orchid biology: reviews and perspectives. Vol. III. Edited by J. Arditti. Comstock Publishing, Cornell University Press, Ithaca, N. Y.

Teoh, E. S. 1980. Asian orchids. Times Books International, Singapore.

Trussell, R. and A. Trussell. 1991. Dendrobiums -- a personal view. Part IV: of Antelopes and Kangaroos (Continued). The Orchid Review 99(12):421-424.

Upton, W. 1989. Dendrobium orchids of Australia. Timber Press, Inc. 9999 Wilshire Blvd. Portland, OR 97225, U. S. A.

Watson, W., and W. Bean. [1890] 1979. Orchids: their culture and management. L. Upcott Gill, London.

Wilfret, G., and H. Kamemoto. 1969. Genome and karyotype relationships in the genus Dendrobium (Orchidaceae). I. crossability. American Journal of Botany 56(5):521-526.

Withner, C. 1974. The orchids, scientific studies. John Wiley and Sons, New York.

Note: These articles are part of the Orchid Species Culture series of books and articles. This part was originally printed January 1997 in Orchids 66(1):42-47.

DENDROBIUM SPECIES CULTURE

Part 3 - Dendrobium bigibbum

Charles and Margaret Baker

Although D. phalaenopsis and D bigibbum are currently, and probably accurately, considered to be separate species, the names have been so confused and are so linked and intertwined that they can probably never be truly separated. We suspect that there are few who are able to say with certainty that their plants are really one or the other, or in the case of hybrids, which species was actually used as a parent. As previously mentioned, the flowers of D. bigibbum tend to be somewhat smaller, have more reflexed sepals and petals, and have a lip that is more rounded or notched instead of being more pointed. We hope that the material contained in these articles will help growers in better understanding their plants and enable them to have more success with growing and blooming these beautiful species and their hybrids.

Dendrobium bigibbum Lindley

AKA: Sometimes spelled D. biggibum. Clements (1989) includes the following synonyms: Callista bigibba (Lindley) Kuntze (revised), Callista sumneri (F. Müeller) Kuntze (revised), D. bigibbum var. album F. M. Bailey, D. bigibbum var. candidum Rchb. f., D. bigibbum subvar. candidum (Rchb. f.) Veitch, D. bigibbum Lindley var. sumneri (F. Müeller) F. M. Bailey, D. phalaenopsis Fitzgerald var. statterianum hort. ex Sander, D. sumneri F. Müeller, and D. bigibbum Lindley subsp. phalaenopsis (Fitzgerald) M. Clements and Cribb. Also see D. lithocola D. Jones and M. Clements, D. phalaenopsis Fitzgerald, and D. striaenopsis M. Clements and D. Jones, the other members of this confused, closely related group of plants.

D. bigibbum and related plants are commonly cultivated and numerous varieties have been described. Some taxonomists currently recognize two subspecies (subsp. phalaenopsis Fitzgerald and subsp. compactum C. White) and several varieties, but others prefer to simply view the plants as a variable complex.

Plants previously known as D. bigibbum subsp. laratensis Clemesha from the Tanimbar Islands have been frequently confused with the Australian D. bigibbum. Clements (1989) indicates that this subspecies has now been formally described as D. striaenopsis M. Clements and D. Jones, and the following names have been listed as synonyms: D. bigibbum Lindley var. albomarginatum Linden Aug. 1891 not F. M. Bailey Mar. 1891, D. bigibbum Lindley subsp. laratensis Clemesha, D. phalaenopsis Fitzgerald var. schroderianum hort. ex Masters, D. schroderianum hort. ex L. Gentil, which Clements indicates is an illegal name. Clements indicates that Blake (1962) includes additional synonyms.

Many plant names that are commonly considered to be synonyms of D. bigibbum were either reinstated as species or described as new species by Clements (1989). The following list is our understanding as to the current status of these names based on Clements' changes. The confusion surrounding the use of the these names remains great, however, and is likely to continue for some time.

D. bigibbum var. albomarginatum F. M. Bailey not Linden. See D. X superbiens Rchb. f.

D. bigibbum var. albomarginatum Linden not F. M. Bailey. See D. striaenopsis M. Clements and D. Jones.

D. bigibbum var. albopurpuratum hort. See D. striaenopsis M. Clements and D. Jones.

D. bigibbum var. compactum C. White. See D. lithocola D. Jones and M. Clements.

D. bigibbum forma compactum (C. White) St. Cloud. See D. lithocola D. Jones and M. Clements.

D. bigibbum subvar. compactum (C. White) St. Cloud. See D. lithocola D. Jones and M. Clements.

D. bigibbum var. georgei C. White. See D. X lavarackianum M. Clements.

D. bigibbum var. macranthum F. M. Bailey. See D. phalaenopsis Fitzgerald.

D. bigibbum var. phalaenopsis (Fitzgerald) F. M. Bailey. See D. phalaenopsis Fitzgerald.

D. bigibbum var. phalaenopsis (Fitzgerald) F. M. Bailey forma compactum (C. White) St. Cloud. See D. lithocola D. Jones and M. Clements.

D. bigibbum var. superbum hort. ex Rchb. f. See D. phalaenopsis Fitzgerald.

D. bigibbum var. superbum subvar. compactum (C. White) Dockrill. See D. lithocola D. Jones and M. Clements.

D. bigibbum var. superbiens (Rchb. f.) F. M. Bailey. See D. X superbiens Rchb. f.

D. bigibbum var. venosum F. M. Bailey. See D. X lavarackianum M. Clements.

D. bigibbum forma venosum (F. M. Bailey) F. M. Bailey. See D. X lavarackianum M. Clements.

ORIGIN/HABITAT: Australia. Plants grow on the northern tip of the Cape York Peninsula. They are generally found west of the dividing range and north of the Iron Range. The habitat extends northward through the islands of the Torres Strait into southern Papua New Guinea. Plants are found in semiarid regions, usually at low elevations, where they grow on small trees and rocks in bright light.

CLIMATE: Station #94175, Thursday Island, Australia, Lat. 10.6S, Long. 142.2E, at 200 ft. (61 m). Record extreme temperatures are 98F (37C) and 64F (18C).

N/HEMISPHERE    JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC
F AVG MAX        82   82   84   86   88   89   87   87   87   86   85   84
F AVG MIN        73   73   74   76   77   78   77   77   77   77   76   74
DIURNAL RANGE     9    9   10   10   11   11   10   10   10    9    9   10
RAIN/INCHES     0.4  0.2  0.1  0.3  1.5  7.0 18.2 15.8 13.9  8.0  1.6  0.5
HUMIDITY/%       75   72   71   70   69   72   79   80   79   77   75   75
BLOOM SEASON     **    *    *    *              *    *   **   **   **   **
DAYS CLR @ 9AM    3    4    3    2    3    1    0    0    1    4    9    5
DAYS CLR @ 3PM    4    5    6    8    7    2    0    1    1    4    8    6
RAIN/MM          10    5    3    8   38  178  462  401  353  203   41   13
C AVG MAX      27.8 27.8 28.9 30.0 31.1 31.7 30.6 30.6 30.6 30.0 29.4 28.9
C AVG MIN      22.8 22.8 23.3 24.4 25.0 25.6 25.0 25.0 25.0 25.0 24.4 23.3
DIURNAL RANGE   5.0  5.0  5.6  5.6  6.1  6.1  5.6  5.6  5.6  5.0  5.0  5.6
S/HEMISPHERE    JUL  AUG  SEP  OCT  NOV  DEC  JAN  FEB  MAR  APR  MAY  JUN



 
 
Cultural Recommendations

LIGHT: 3000-4000 fc. The heavy summer cloud cover indicates that some shading is needed from spring through autumn, but light should be as high as the plant can tolerate, short of burning the leaves. Strong air movement should be provided year-round.

TEMPERATURES: Throughout the year, days average 82-89F (28-32C), and nights average 73-78F (23-26C), with a diurnal range of 9- 11F (5-6C).

HUMIDITY: 70-80% year-round.

FERTILIZER: 1/4-1/2 recommended strength, applied weekly. A high- nitrogen fertilizer is beneficial from spring to midsummer, but a fertilizer high in phosphates should be used in late summer and autumn.

REST PERIOD: Growing temperatures should be maintained year- round. Some growers report success with winter minimums near 54F (12C). It should be noted, however, that this is colder than the record lows in the habitat. In cultivation, these extremes should probably be avoided; but seed-grown plants are somewhat adaptable and may adjust to these conditions, especially if they are kept very dry. A long dry rest is required in winter. Many growers recommend hanging plants high in the greenhouse and forgetting them for 2-3 months in winter. However, a little rain does fall each month, so an occasional early morning misting should help keep plants from becoming too dry. Growers should maintain high light levels, provide strong air movement, and eliminate fertilizer until watering is resumed in spring. After growth starts, Australian growers strongly recommend using care to keep water from the new growths until they are 2-3 in. (5-8 cm) tall.

GROWING MEDIA: Plants may be mounted or potted. If plants are potted, the pots should be as small as possible and the medium should be very open and fast draining. Excellent drainage is essential. Repotting is best done when the new growth is 2-3 in. (5-7 cm) high and new root growth is evident.

MISCELLANEOUS NOTES: The bloom season shown in the climate table is based on collection reports. Growers indicate that D. bigibbum does poorly in Singapore, as it requires a more seasonal climate.

One source indicates that plants are free blooming with peak blooming Aug.-Nov. (Feb.-Mar. in the southern hemisphere) and that both slightly cooler average temperatures and shorter days (long periods of dark) are required to initiate blooms. It should be remembered, however, that the record low temperature in the habitat is 64F (18C) and conditions colder than this should probably be avoided.

Sudden temperature declines may cause flower buds to drop, and cold water should be avoided when plants are in bud. Other growers suggest that bud drop may be caused if plants are allowed to dry out, if humidity is too low, if ethylene gas contaminates the growing area, or if salts are allowed to accumulate.

Australian growers recommend repotting D. bigibbum every other year in the smallest possible pots. They also suggest removing all but the newest 4-5 stems. The base of the plants should be kept clean and healthy. Plants seldom develop into specimen plants as they are very prone to die back.

Plant and Flower Information

PLANT SIZE AND TYPE: A slender, 16-48 in. (40-122 cm) sympodial epiphyte or lithophyte.

PSEUDOBULB: 16-48 in. (40-122 cm) long. The stems are cylindrical with a slight swelling at the base.

LEAVES: 3-12 per growth. The oblong-lanceolate leaves are 3-6 in. (8-15 cm) long. They are flushed with red or purple, and are leathery, rigid, and evergreen for 2 years. The apical 30% of the stems are leafy.

INFLORESCENCE: 8-16 in. (20-41 cm) long. Each year, over a period of several years, each growth produces 1-4 inflorescences from nodes near the apex of the pseudobulb. Flower production may continue even after the canes are leafless. The inflorescences are usually arching or horizontal, but they may be pendent. Flowers are nicely spaced along the upper half of the raceme.

FLOWERS: 8-20 per inflorescence, occasionally less. The flowers are 1.2-2.0 in. (3-5 cm) across. Sepals and petals usually curve backward. The showy flowers have a heavy texture, broad overlapping sepals, and narrower petals. Flowers are normally violet, but colors include white, pale to deep lilac, magenta, and purple. All colors are bright and rich. The pubescent lip, which is normally rounded or notched in the center of the blunt midlobe, is often a darker shade than the sepals and petals. Blossoms are highly variable in size and color. Flowers last for months in perfect condition, providing they do not become water spotted, so the plants seem to be in nearly continuous bloom.

HYBRIDIZING NOTES: Chromosome count is 2n = 38 as D. bigibbum and D. bigibbum var. bigibbum . As D. bigibbum var. compactum the count is 2n = 38 and 2n = about 57. As D. bigibbum var. superbum the count is n = 19 and 2n = 38.

Johansen (1990) indicates that the seeds produced when D. phalaenopsis was self-pollinated contained no visible embryos and no seeds germinated. Capsules opened 197 days after pollination. Seeds are sufficiently mature for green-pod sowing in 120-140 (131) days.

Wilfret and Hashimoto (ref. 568) did not get seed when they tried to cross D. bigibbum with D. leonis (Lindley) Rchb. f. or D. crumenatum Swartz. When D. bigibbum was crossed with D. delacourii Guillaumin, seed was occasionally produced but none was viable. D. bigibbum regularly produces a high percentage of viable seed when different clones are cross-pollinated.

As a parent, D. bigibbum contributes long-lasting flowers, full flower shape, and long inflorescences thereby improving a hybrid's potential value for cut flowers. It does not breed true for color.

D. bigibbum hybridizes naturally with D. discolor Lindley producing D. X superbiens Rchb. f.

REFERENCES:

Australasian Native Orchid Society (Victoria Group). 1984. Cultivation of Australian native orchids. Australasian Native Orchid Society, Inc., Melbourne, Australia.

Australasian Native Orchid Society. 1990. 'Proceedings' first Australasian native orchid conference and show. Australasian Native Orchid Society, Inc., Wollongong, N. S. W., Australia.