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ORCHID SPECIES CULTURE Charles and Margaret Baker Chysis aurea Lindley AKA: Plants of the genus Chysis, while widespread, are rather uncommon. There has been and continues to be considerable confusion regarding the status of several species. Some authorities consider Chysis aurea and Chysis laevis to be synonymous and have listed these plants as Chysis aurea with distribution from Mexico, through Central America, to Venezuela, Colombia and Peru. Most authorities now, however, seem to consider plants from Mexico and northern Central America to be Chysis laevis, while plants from South America are considered to be Chysis aurea. Although very similar, the flowers of C. laevis are reportedly larger, have slight differences in the keels on the lip, and are somewhat differently colored than those of those of C. aurea. ORIGIN/HABITAT: Venezuela, Colombia, and possibly northward into Panama. Variety maculata is reported as far north as Costa Rica. Plants are normally found at lower elevations in dense, moist forests where they grow high up in tall trees, mainly on the trunks or the basal part of large branches. In Venezuela, plants were found near Caracas at about 2500 ft. (760 m) in a damp section of forest near a ravine with running water. CLIMATE: Station #80416, Caracas, Venezuela, Lat. 10.5N, Long. 66.8W, at 2760 ft. (841 m). Temperatures are calculated for an elevation of 2500 ft. (760 m), resulting in probable extremes of 92F (33C) and 46F (8C). N/HEMISPHERE JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC F AVG MAX 76 78 80 82 81 79 79 80 81 80 78 79 F AVG MIN 57 57 59 61 63 63 62 62 62 62 61 59 DIURNAL RANGE 19 21 21 21 18 16 17 18 19 18 17 20 RAIN/INCHES 0.9 0.4 0.6 1.3 3.1 4.0 4.3 4.3 4.2 4.3 3.7 1.8 HUMIDITY/% 77 74 73 74 80 80 80 79 79 81 83 81 BLOOM SEASON * * * ** ** * ** * * DAYS CLR N/A RAIN/MM 23 10 15 33 79 102 109 109 107 109 94 46 C AVG MAX 24.4 25.6 26.7 27.8 27.2 26.3 26.2 26.7 27.2 26.7 25.6 26.1 C AVG MIN 13.9 13.8 14.9 16.0 17.1 17.1 16.6 16.6 16.6 16.6 16.0 14.9 DIURNAL RANGE 10.5 11.8 11.8 11.8 10.1 9.2 9.6 10.1 10.6 10.1 9.6 11.2 S/HEMISPHERE JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN Cultural Recommendations: LIGHT: 2500-3500 fc. Light should be somewhat filtered or diffused, and plants should not be exposed to direct midday sun. Strong air movement should be provided at all times. TEMPERATURES: Summer days average 79-80F (26-27C), and nights average 62-63F (17C), with a diurnal range of 16-18F (9-10C). HUMIDITY: 75-80% year-round. Conditions may be somewhat more humid in the habitat, however. WATER: Rainfall is moderate to heavy from late spring into autumn. Amounts then diminish into a 3-4 month winter dry season. Cultivated plants should be watered heavily while actively growing, but the medium must not be allowed to become stale or soggy. Water should be reduced in late autumn after new growths have matured. 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: Winter days average 76-79F (24-26C), and nights average 57-59F (14-15C), with a diurnal range of 19-21F (11-12C). Rainfall is low in winter, but additional moisture is generally available during nights and early mornings from heavy dew and mist. Water should be reduced for cultivated plants in winter, but they should not be allowed to remain dry for long periods. Fertilizer should be reduced or eliminated until new growth starts and heavier watering is resumed in spring. GROWING MEDIA: Because of the pendent growth habit, these plants are probably more easily managed if grown mounted on a slab of rough bark or tree-fern fiber. Humidity must be kept high for mounted plants, however, and they must be watered at least once daily in summer. Several waterings a day may be necessary for mounted plants during extremely hot dry weather. Plants also grow well in hanging pots or baskets that allow the growths to hang naturally and are filled with an open, fast draining medium that enables the roots to dry rapidly after watering. For plants in pots or baskets, many growers recommend using a shredded tree-fern fiber as a medium because it breaks down more slowly than bark and, therefore, requires repotting less often. Some growers also recommend adding perlite and large chunks of charcoal to the potting mix. Because these plants do not usually respond well when disturbed, repotting or dividing should be done only when the medium breaks down or the plant has overgrown its container. When repotting or dividing is necessary, however, it should be done only when new root growth is just starting. This allows the plant to become established in the shortest possible time with the least amount of stress. MISCELLANEOUS NOTES: The bloom season shown in the climate table is based on cultivation records. Plant and Flower Information: PLANT SIZE AND TYPE: A relative large, descending to pendent sympodial epiphyte with growths that may reach 20 in. (50 cm) long. PSEUDOBULB: 20 in. (50 cm) long. The spindle-shaped pseudobulbous stems are completely enveloped by the sheathing bases of the leaves. These remain around the stems as dry, gray sheaths, even after the leaves have fallen. The pseudobulbs of C. aurea are relatively slender when compared with other species in the genus. LEAVES: To 12 in. (30 cm) long but about 2 in. (5 cm) wide. Several medium to light green leaves are produced along the length of the pseudobulb. They are thin, somewhat wavy, rather soft-textured, strongly ribbed, taper to a sharp point at the tip, and are deciduous at the end of the growing season. INFLORESCENCE: To about 12 in. (30 cm) long, but usually shorter. The inflorescence is produced from the axils of the new growth before the leaves have developed. FLOWERS: 6-12 long-stalked, waxy, long-lived, fragrant blossoms are produced on each inflorescence. The flowers are 1.6-3.0 in. (4.0-7.5 cm) across but are usually about 2 in. (5 cm) and are somewhat variable in the size and shape of the floral segments. The fleshy sepals and petals are pale yellow at the base, yellow at the apex, with most of the inner surface flushed with red to orange-brown. The fleshy, whitish lip, which is marked with red-brown, is about 0.8 in. (2 cm) long and about 0.8 in. (2 cm) wide if the normally upright side lobes are spread. The lip has five parallel keels of equal length extending from the base to the midpoint. The flowers of C. aurea variety maculata from Panama and Costa Rica are said to be somewhat smaller than those of the type but are more brightly colored. HYBRIDIZING NOTES: N/A. REFERENCES: . Bechtel, H., P. Cribb, and E. Launert. 1980. Manual of cultivated orchid species. MIT Press, Cambridge, Mass. Dressler, R. 1993. Field Guide to the orchid of Costa Rica and Panama. Cornell University Press. New York. Dunsterville, G., and L. Garay. 1965. Venezuelan orchids illustrated, vol. 3. Orchid Herbarium of Oakes Ames, Botanical Museum, Harvard University, Cambridge, Mass. Fowlie, J. 1971. Obscure species: Three distinctive species of Chysis from Central America. Orchid Digest 35(3):85-87. Hamilton, R. 1988. When does it flower? 2nd ed. Robert M. Hamilton, 9211 Beckwith Road, Richmond, B.C., Canada V6X 1V7. Hawkes, A.  1987. Encyclopaedia of cultivated orchids. Faber and Faber, London. Pridgeon, A. ed. 1992. The illustrated encyclopedia of orchids. Timber Press, Portland, OR. Pridgeon, A. 1986. Melting pot. American Orchid Society Bulletin 55(8):812-814. Dressler, R. 1993. Field Guide to the orchid of Costa Rica and Panama. Cornell University Press. New York. Williams, L., and P. Allen. [1946-1949] 1980. Orchids of Panama. Monographs in systematic botany, vol. 4. Missouri Botanical Garden, St. Louis, Mo. PHOTOS/DRAWINGS: . Copyright 1997, Charles O. Baker and Margaret L. Baker Sheet version 566488 ......................................................................... 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. 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