Oncidium is an extraordinarily large and diverse New World genus with an equally diverse number of habitats. Oncidiums may originate anywhere from sea level in the tropics to the high elevations of the Andes. This obviously makes cultural generalizations difficult. More specific instructions may be available from the grower. Some genera included are Aspasia, Brassia, warm-growing miltonias (often called the Brazilian type) and many of their hybrids.
Oncidium was first described by O. Swartz in 1800 in Kungliga Svenska Vetenskapakademiens Avhandlingar. The name is derived from the Greek word onkos (for mass or pad). The genus is not only one of the largest and most popular cultivated orchid genera, it is also a conglomeration of considerably distinct species that have given taxonomists serious problems. During the last 25 years many species have been shifted to new genera or transferred to other, existing genera, notably Cyrtochilum, Psychopsis, Tolumnia and Trichocentrum.