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ORCHID SPECIES CULTURE Charles and Margaret Baker Psychopsis sanderae (Rolfe) E. Lückel & G. J. Braem AKA: Oncidium sanderae Rolfe. During the years 1961-1989, plants collected in Ecuador, Peru, and Bolivia that were actually Psychosis versteegianum were misidentified as Psychopsis sanderae. As a result, there are undoubtedly many plants of Psychosis versteegianum that are mislabeled as Psychopsis sanderae. The true Psychopsis sanderae was rediscovered in 1989, but we were told that the site where the plants were found has now been destroyed as orchid habitat. ORIGIN/HABITAT: Peru. These plants were rediscovered in the Department of Junin, but the exact locality and elevation were not reported. They were growing high up the trunks of trees and on large branches in wet mountain forests. Habitat elevation was not reported, so we have estimated it at 4000 ft. (1220 m) based on reports from others. Consequently, growers should use the temperatures indicated in the following table and resulting Cultural Recommendations cautiously. CLIMATE: Station #84534, Tingo Maria, Peru, Lat. 9.1S , Long. 75.9W, at 2106 ft. (642 m). Temperatures are calculated for an estimated elevation of 4000 ft. (1220 m), resulting in probable extremes of 91F (33C) and 33F (1C). N/HEMISPHERE JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC F AVG MAX 80 82 82 81 81 81 80 79 80 80 81 80 F AVG MIN 57 58 58 59 59 60 60 60 60 60 59 58 DIURNAL RANGE 23 24 24 22 22 21 20 19 20 20 22 22 RAIN/INCHES 5.8 8.2 8.0 15.9 24.9 12.0 15.9 16.4 22.8 8.5 8.7 4.5 HUMIDITY/% 78 76 77 79 78 80 81 81 81 80 78 79 BLOOM SEASON N/A DAYS CLR @ 7AM 2 3 3 1 1 1 0 0 0 1 1 1 DAYS CLR @ 1PM 15 12 9 3 4 4 4 1 4 2 7 12 RAIN/MM 147 208 203 404 632 305 404 417 579 216 221 114 C AVG MAX 26.7 27.8 27.8 27.2 27.2 27.4 26.7 26.1 26.7 26.7 27.2 26.7 C AVG MIN 13.9 14.3 14.3 14.9 14.9 15.4 15.4 15.4 15.4 15.4 14.9 14.3 DIURNAL RANGE 12.8 13.5 13.5 12.3 12.3 12.0 11.3 10.7 11.3 11.3 12.3 12.4 S/HEMISPHERE JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN Cultural Recommendations: LIGHT: 1800-2500 fc. Plants may tolerate higher light if humidity is high and air movement is brisk. TEMPERATURES: Throughout the year, days average 79-82F (26-28C), and nights average 57-60F (14-15C), with a diurnal range of 19-24F (11-14C). The warmest days, coolest nights, and greatest diurnal range occur in late winter. HUMIDITY: 75-80 % year-round. WATER: Rainfall is very heavy throughout the year. Conditions in specific habitat may not be as wet as the region around Tingo Maria. Cultivated plants should be watered often, but the roots must dry rapidly after watering, and the medium should never become soggy and sour. FERTILIZER: 1/4-1/2 recommended strength, applied weekly during periods of active growth. Many growers recommend using a balanced fertilizer all year. If plants are being grown in the higher latitudes where light may be low or temperatures might be cool, fertilizer should be reduced anytime the plants are not actively growing to prevent a salt buildup in the medium. REST PERIOD: Growing conditions should be maintained all year. Growers are reminded that the temperatures indicated in the climate table are based on estimated habitat elevation and should be used with caution. Water may be reduced somewhat in winter, especially for plants grown in the dark, short-day conditions common in temperate latitudes. They should not dry out or be dry for long periods. If water is reduced, fertilizer should also be reduced until water is increased in spring. GROWING MEDIA: Plants may be mounted on tree-fern or cork slabs if humidity is high and plants are watered at least once daily in summer. Mounted plants may need several waterings a day during very hot, dry weather. Many growers have trouble keeping mounted plants moist enough, and prefer to grow plants in shallow pots or baskets using an open, fast draining medium which contains materials that retain some moisture, such as chopped sphagnum or perlite, but dries fairly rapidly after watering. Charcoal is often added to help keep the medium open and prevent it from becoming sour. Undersized pots just large enough to hold the roots should be used. Repotting should be done only when necessary, and then only just as new root growth is starting so that the plant can become reestablished in the shortest possible time. As with the other species in the genus, these plants should grow well in a wire basket lined with coconut fiber and then filled with a mixture of fine- and medium-grade tree-fern fiber mixed with about 10% perlite and 10% charcoal. MISCELLANEOUS NOTES: In the habitat, plants probably bloom sporadically during many months of the year. Plant and Flower Information: PLANT SIZE AND TYPE: A clump-forming, 6-10 in. (15.5-24.5 cm) sympodial epiphyte. PSEUDOBULB: 1.4-1.8 in. (3.6-4.6cm) long by 1.2-1.5 in. (3.0-3.8 cm) wide. The laterally compressed pseudobulbs are egg-shaped to elliptical in outline. The wrinkled surfaces are normally dull purple often mixed with dull green. LEAVES: 5-8 in. (12-20 cm) long. A single, leathery, leaf is carried at the top of each pseudobulb. The narrowly oblong-elliptic leaf is 1.2-1.6 in. (3-4 cm) wide, tapers to a sharp point at the tip, and tapers to a short, folded petiole at the base. The upper surface is pale grayish purple with dull, opaque, pale green blotches and coalesced spots. The underside is dull purple with opaque, pale green flecks and dots. INFLORESCENCE: 14 in. (35 cm) long. The erect, lightly flexuous peduncle, which is broadly elliptic in cross section, emerges from the base of the most recently matured pseudobulb. It has internodes spaced 1.5-1.7 in. (3.8-4.4 cm) apart. Each slightly swollen node is covered by a thin, dry, membranelike, tubular bract that is about 0.8 in. (2 cm) long. The peduncle is dull green with a dense covering of dark brownish purple markings that are less numerous on the upper part of the growth. FLOWERS: 1 at a time, 2-4 per inflorescence. Each inflorescence produces 2-4 blossoms one after another. After flowering is over on the primary spike, it often produces a lateral branch that develops from one of the upper nodes. Flowers are 5-6. (13-15 cm) tall by about 2 in. (5 cm) across. The tips of the petals and dorsal sepal are dark reddish brown that shades to pale brown on the basal 1/4. Lateral sepals are bright, clear yellow marked with comparatively small red-brown blotches. The lip is a brilliant greenish yellow with numerous, small, sharply defined red spots and blotches around the border of midlobe. The callus is dull white marked with chestnut-brown. The dark purplish brown column has medium brown fringed, comb-like wings with very dark brown glandular tips. The anther is pale yellowish green with a dark brownish purple tip divided by a broad yellowish green stripe. The erect petals and dorsal sepals are about 4 in. (10 cm) long by about 0.2 in. (0.5 cm) wide, with the dorsal sepal being slightly wider and folded as well as bent slightly to one side at the apex. The sickle-shaped lateral sepals, which are about 2.2 in. (5.8 cm) long by 0.6 in. (1.5 cm) wide, have strongly crisped margins. The 3-lobed lip is approximately 2 in. (5 cm) long by 0.8 in. (2 cm) across the expanded lateral lobes by 1.8 in. (4 cm) wide across the fully open mid-lobe. The margins of the mid-lobe are very crisped, and it is deeply notched at the apex. The callus, which is at right angles to the column, is broad at the base with a thick outer edge with 2 knobs. Its thick mid-section is divided in 3 with 2 lateral subconical teeth separated by a free apex. The stout, erect column is abruptly dilated at the apex. HYBRIDIZING NOTES: Chromosome count is 2n = 38. REFERENCES: . Bennett, D. E. Jr. and E. Christenson. 1993. Icones Orchidacearum Peruviarum. Pub. privately by A. Pastorelli de Bennett. Braem, G. J. 1993. Studies in the Oncidiinae. Schlechteriana 4(1-2):8-29. Index kewensis S18. Orchidee, 33(1): 6 (1982) Rolando, I. and E. Christenson. 1993. Peruvian Orchids. The rediscovery of Psychopsis sanderae (Rolfe) Lückel & Braem and elucidation of Psychopsis versteegianum (Pulle) Lückel & Braem. Orchid Digest 57(3):116-118. Schweinfurth, C. 1958-1961. Orchids of Peru. Fieldiana: Botany 30(1-4). Chicago Natural History Museum Press, Chicago. Copyright 2000, Charles O. Baker and Margaret L. Baker Sheet version 94436922 ......................................................................... 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. __________________________________________________________________________