Tolumnia

Tolumnia is a genus of 27 species of tropical, epiphytic herbaceous perennials in the orchid family (Orchidaceae). They are native to Mexico, Central America, northern South America, and islands in the Caribbean. One species, Tolumnia bahamensis, has a foothold in the US, in Florida. The genus name is probably derived from Tolumnius, a character mentioned by Virgil.

In nature, these miniature plants are twig epiphytes, growing in exposed conditions on the twigs of shrubs and trees. Mimic these conditions by mounting the plants on small bark mounts or growing them in restrictive, small, terracotta pots. Dancing lady orchids need bright light (a south-facing window is ideal), warm temperatures and regular watering throughout the year. The roots of dancing lady orchids need frequent watering, but they must dry out quickly. They should not be allowed to stay dry for too long, as they need rapid wet/dry cycles. 

These species were formerly included in the genus Oncidium as the “equitant oncidiums.” The term equitant refers to the way the fan of sheathing leaves “ride” one another (like an equestrian straddling a horse). Many irises have a similar growth form. The plants have a fan of leaves and produce new plants as offshoots on short rhizomes. The inflorescences arise in the axils of the leaves. They produce sprays of elaborately marked and patterned flowers. The dorsal sepal and petals are free and narrow. The lip is very large and semicircular, obscuring the lateral sepals. The lip is like the skirt of a dress and the callus on the lip is like a bodice. Consequently, these orchids (and many Oncidium species) are called dancing lady orchids. Flowers come in shades of yellow, orange, red, or white, with contrasting markings.

Insects, Diseases, and Other Plant Problems:  Dancing lady orchids are susceptible to the usual pests of houseplants and greenhouse plants, including mealybugs, scale insects and thrips. Roots can rot if the growing medium does not dry out rapidly.