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ORCHID SPECIES CULTURE Charles and Margaret Baker Laelia tenebrosa (Gower) Rolfe AKA: Laelia grandis var. tenebrosa Gower. ORIGIN/HABITAT: Brazil. The habitat is generally thought to extend from southern Bahia to northern Espírito Santo. Miranda (1990), however, reported that the habitat is limited to a very small area in southern Espírito Santo where plants grow on large trees in dense forest. He further stated that this limited habitat has been totally destroyed and that this species, which has always been rather rare, is now impossible to find in nature. Even with all that has been written about this large, showy species, few details of habitat location and elevation are available. Therefore, the habitat location and elevation is estimated based on the habitats of other species known to grow in the same habitat and to hybridize naturally with Laelia tenebrosa. However, growers should use the resulting Cultural Recommendations with caution. CLIMATE: Station #83648, Vitória, Brazil, Lat. 20.3S, Long. 40.3W, at 13 ft. (4 m). Temperatures are calculated for an estimated elevation of 1500 ft. (460 m), resulting in possible extremes of 97F (36C) and 38F (3C). N/HEMISPHERE JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC F AVG MAX 72 73 73 75 76 79 81 82 81 78 76 74 F AVG MIN 60 60 62 64 65 67 68 68 68 66 63 61 DIURNAL RANGE 12 13 11 11 11 12 13 14 13 12 13 13 RAIN/INCHES 2.2 2.1 2.7 4.2 5.7 6.3 3.7 3.0 5.2 3.9 2.3 3.4 HUMIDITY/% 83 84 86 84 86 85 82 83 84 85 82 84 BLOOM SEASON * * * ** *** ** * * * * * DAYS CLR @ 9AM 10 12 6 3 2 2 6 6 7 8 12 13 RAIN/MM 56 53 69 107 145 160 94 76 132 99 58 86 C AVG MAX 22.2 22.8 22.8 23.9 24.4 26.3 27.3 27.8 27.2 25.6 24.4 23.3 C AVG MIN 15.6 15.6 16.7 17.8 18.4 19.5 20.1 20.1 20.1 18.9 17.3 16.2 DIURNAL RANGE 6.6 7.2 6.1 6.1 6.0 6.8 7.2 7.7 7.1 6.7 7.1 7.1 S/HEMISPHERE JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN Cultural Recommendations: LIGHT: 3500-4000 fc. Some growers report that bright light is essential to initiate blooms, but full sun should be avoided. Others, however, report successful flowering with about 2500 fc of light. If plants do not bloom because brighter conditions are needed, light should be increased gradually to allow the plant time to adapt. Strong air movement should be provided at all times. TEMPERATURES: Summer days average 79-82F (26-28C), and nights average 67-68F (20C), with a diurnal range of 12-14F (7-8C). Growers report that plants are healthy when temperatures drop to 60F (16C) or increase to 100F (38C) for short periods. Note however, that these high temperatures are outside the normal extremes estimated for the habitat. Water should be reduced if temperatures are cool and increased anytime temperatures are hot. HUMIDITY: Near 85% year-round. WATER: Rainfall is moderate to heavy most of the year with somewhat drier conditions for about 3 months in winter, but average rainfall may be somewhat greater in the higher elevation habitat. Cultivated plants should be watered heavily while actively growing, but the roots must always dry rapidly after watering. Water should be reduced somewhat after new growths mature in autumn. FERTILIZER: 1/4-1/2 recommended strength, applied weekly while plants are actively growing. A high-nitrogen fertilizer is beneficial from spring to midsummer, but a fertilizer high in phosphates may be used in late summer and autumn. REST PERIOD: Winter days average 72-74F (22-23C), and nights average 60-61F (16C), with a diurnal range of 12-13F (7C). Rainfall in the habitat is somewhat lower in winter, but the high humidity indicates that some additional moisture is generally available from mist and heavy dew. Cultivated plants need less water in winter, particularly if grown in the dark, short-day conditions common in temperate latitudes. Plants should never dry out completely, however. Fertilizer should be reduced or eliminated until heavier watering is resumed in spring. GROWING MEDIA: Small pots or baskets may be filled with a very coarse, open, fast-draining medium that allows the roots to dry rapidly after watering. Undersized pots with room for only 1-2 years' growth are recommended because the medium in larger pots remains wet for too long after watering. If the roots do not dry quickly, they eventually die from root rot. Most growers recommend using coarse-sized fir bark in either clay or plastic pots, but others prefer clay pellets from concrete manufacturers in clay pots. Plants also grow well mounted on tree-fern or cork slabs, but humidity must be high and plants need at least daily watering in summer. Mounted plants may need several waterings a day during extremely hot, dry weather. Repotting or dividing should be done only when new root growth is just starting. MISCELLANEOUS NOTES: The bloom season shown in the climate table is based on cultivation records. In nature, plants bloom in early summer. Although this species is rare if not extinct in nature, plants are still readily available for cultivation as the better forms are now widely grown from seed-propagated populations. Growers consider this a difficult plant to grow successfully, so careful attention should be given its cultural requirements. Plant and Flower Information: PLANT SIZE AND TYPE: An 18 in. (46 cm) sympodial epiphyte. PSEUDOBULB: To 7 in. (18 cm) long by about 1.2 in. (3 cm) wide. The club-shaped pseudobulbs are covered with sheaths that become dry and papery with age. The robust plants sometimes have a purplish brown tint on the pseudobulbs and leaves. Some growers indicate that plants seldom become large since an old growth tends to die as a new lead growth develops, and plants almost never break multiple leads. LEAVES: About 11 in. (28 cm) long by 2.4 in. (6 cm) wide. The leaves of cultivated plants may reach a length of 15 in. (38 cm). A single erect, leathery leaf is carried at the top of each pseudobulb. Leaves range from oblong to egg-shaped to straplike and are rounded at the tip. INFLORESCENCE: 12 in. (30 cm) long. An erect flower spike emerges through a wide, flat sheath at the top of the most recently matured pseudobulb. FLOWERS: 2-3. The large, showy, fragrant blossoms are frequently 7 in. (18 cm) across. They usually last about 2 weeks. The narrow, bronze or coppery sepals and petals, which sometimes are twisted slightly, are usually almost flat with slightly wavy margins, especially on the petals. The 3-lobed lip has large sidelobes that roll upward to form a tube around the column. The resulting large, trumpet-shaped lip has a deep purple ring at the base of the flaring midlobe with a lighter colored margin toward the ruffled, reflexed apex. The throat is yellow with prominent veins that extend over the disc to the margin of the lip. Several color variations are known in cultivation, including an alba form with green sepals and petals and a white lip. The very old cultivar 'Walton Grange' has nankeen-yellow sepals and petals and a white lip decorated with purple markings. HYBRIDIZING NOTES: N/A. REFERENCES: Bechtel, H., P. Cribb, and E. Launert. 1980. Manual of cultivated orchid species. MIT Press, Cambridge, Mass. Hamilton, R. 1988. When does it flower? 2nd ed. Robert M. Hamilton, 9211 Beckwith Road, Richmond, B.C., Canada V6X 1V7. Hamilton, R. Orchid Nurse. Hawkes, A.  1987. Encyclopaedia of cultivated orchids. Faber and Faber, London. Miranda, F. E. 1990. Brazilian laelias - Part I: Section Cattleyodes. American Orchid Society Bulletin, 59(3): 234-245. Withner, C. 1990. The cattleyas and their relatives, vol. II:the laelias. Timber Press, Portland, OR. PHOTOS/DRAWINGS: Bechtel, H., P. Cribb, and E. Launert. 1980. Manual of cultivated orchid species. MIT Press, Cambridge, Mass. Miranda, F. E. 1990. Brazilian laelias - Part I: Section Cattleyodes. American Orchid Society Bulletin, 59(3): 234-245. Withner, C. 1990. The cattleyas and their relatives, vol. II:the laelias. Timber Press, Portland, OR. Copyright 1997, Charles O. Baker and Margaret L. Baker Sheet version 25626971 ......................................................................... Please remember that this sheet is for your use only, and though it was provided free of charge, it may not be reproduced or retransmitted in any way without permission. ......................................................................... __________________________________________________________________________ "Orchid Species Culture" Charles & Margaret Baker, Portland, Oregon USA Orchid Culture & Pollination site http://www.orchidculture.com email <firstname.lastname@example.org> __________________________________________________________________________ "Orchid Species Culture Vol. 1 - Pescatorea, Phaius, Phalaenopsis, Pholidota, Phragmipedium, Pleione" 250 pages of culture information. "Orchid Species Culture Vol. 2 - Dendrobium" 850 pages of culture information for more than 1230 Dendrobium species. "The genus Paphiopedilum--Natural History and Cultivation" - Part 1 Dr. Guido Braem, Charles and Margaret Baker ISBN 0-9665337-0-4 Full page color photograph of each species. "The genus Paphiopedilum--Natural History and Cultivation" - Part 2 Dr. Guido Braem, Charles and Margaret Baker ISBN 0-9665337-1-2 Full page color photograph of each species. "Orchid Species Culture Vol. 3 - The Laelia/Cattleya Alliance" coming in a few months. __________________________________________________________________________