AAOS Study Group ****************************************************************************** The 7th meeting of the Orchid Study Group was July 13. Our topic was Oncidiums, the dancing lady orchids. In nature, Oncidiums are found in the New World Tropics, ranging from Florida and Mexico through Central and much of South America. Most species are from Brazil, the Colombian Andes, Ecuador and Peru. There are more than 750 species. They grow in a great variety of habitats from sea level to 13,000 feet. Yellow and brown are the most common colors but there is an entire range of color from green to purple. In general, many Oncidiums can be grown in intermediate conditions and need good light. They all need frequent watering with a drying out between waterings. Most need to be repotted each year, except those that have hard, round pseudobulbs. These need less watering and repotting only every 3 to 4 years. A well-drained compost of mostly fir bark or osmunda fiber is good. Also, growing on logs or bark give good conditions. The roots are fine and numerous and need to dry between waterings. The Oncidiums without pseudobulbs need a severe drying out after flowering. Fertilizing needs to be done weekly while the plant is growing. In the recommended doses, the green parts will grow but the plant won't flower. It's necessary to cut down on nitrogen to get flowering. Humidity at 55-60% is recommended along with constant air movement. A cool, light breeze will help the roots dry quickly. We used the book Orchids Care and Cultivation by LeRoy-Terquem and Parisot. The chart on page 161 was very useful, describing the needs of the 4 different groups of Oncidiums. Next Meeting: Saturday, September 13, 10:00 AM at Susan Crippen's greenhouse in Ann Arbor. Topic: Her Greenhouse and the odd Bulbophyllums that she grows. Call Paige at (313) 426-2704 for directions.                     *****************************************      ******************************************************************************