The dancing ladies are coming, but don't look for them on the dance floor. You'll find them in the produce section of grocery stores or the indoor gardening section of the box stores. These dancing ladies are Oncidium orchids, which get their name from a distinctive shape that resembles the flowing skirt of a dancing woman.

Oncidiums sold for the home market put on a colorful show that's different from the Phalaenopsis orchids that consumers are used to seeing. Phalaenopsis orchids have broad, flat leaves and produce perhaps a dozen large flowers in white, pink, purple and a variety of mottled colors (including a jarring blue that's the result of a dye). Oncidium orchids, on the other hand, typically have thin leaves and produce long, branching sprays of numerous, small yellow flowers.

Both types of orchids are imported from Taiwan, where some species of Phalaenopsis grow naturally. Oncidiums are joining Phalaenopsis on store shelves due to an agreement between the U.S. Department of Agriculture and the Taiwanese government. The agreement allows Taiwan orchid growers to ship the plants in a growing medium like sphagnum moss to the United States. Prior to the ruling, which became effective March 7, Taiwan could only ship Oncidiums bare root to the U.S. Without the protective growing medium, the plants had be shipped quickly by overnight air, making it prohibitively expensive to transport them in large quantities.

Some Taiwan orchid growers have already filed applications to export Oncidiums to the U.S. Taiwanese officials said it will take at least four months to get the plants ready for shipping and couldn't say when the plants will be will be available to American consumers.

Potted Oncidium orchidThe change in the rule that allows Taiwan orchid growers to export Oncidiums to the U.S. is similar to a 2004 decision that allowed them to ship Phalaenopsis to U.S. markets. That decision led to the exotic Phalaenopsis orchid becoming a popular and affordable choice for flowering houseplants. In 2015, Taiwan exports of Phaalenopsis orchids to the United States were valued at $50 million, according to Taiwan's Bureau of Animal and Plant Health Inspection and Quarantine, Council of Agriculture, Executive Yuan. In contrast, Taiwan's exports of Oncidiums to the United States were valued at $8 million in 2015.

"These Oncidium plants still have to be grown in moss in USDA-approved greenhouses in Taiwan, like the Phalaenopsis orchids," said Norman Fang, a leading orchid expert who has won more than 300 American Orchid Society awards and owns Norman's Orchids in Montclair, California. The Oncidiums, like the Phalaenopsis, will be subject to specific growing, inspection and certification requirements to prevent a quarantine plant pest from being introduced to the U.S., Fang added.

Here are some tips on how to care for Oncidium orchids provided by Yin-Tung Wang, an adjunct professor in the Department of Horticultural Sciences in the Texas A&M; University in College Station. (Wang played a key role in the discussions that led to the change in importation rules for Phalaenopsis orchids.)

Oncidium orchid care

Light: Bright, but never direct sun.

Temperature: 50 to 80 degrees Fahrenheit

Water: Allow the medium to go nearly dry and then water thoroughly. Sphagnum moss is difficult to re-wet if it gets bone dry.

Relative humidity: 50-80 percent.

Fertilizer: A soluble fertilizer at 1/2 to 1/4 teaspoon per gallon of water, but only every two to three waterings. When not using water in the fertilizer, it's important to thoroughly flush the pots with water to prevent a buildup of fertilizer salts, which can "burn" the roots.

After flowering: Cut off the flowering spike where it emerges from the plant.

Repotting: After flowering, and then every two years. Choose a pot size that's just bigger than the roots; don't base your choice on the leaves. Take care not to choose too big a pot, which can lead to root rot.

Re-flowering: This occurs when a new growing shoot has matured. Old growths will not re-bloom.

Phalaenopsis orchid care

Similar to care for Oncidiums, except that Phalaenopsis will rebloom in less light than Oncidiums and old flower spikes may rebloom as long as the flowering spike remains green. If the flowering spike turns the color of straw, cut it off where it emerges from the plant. A "trick" to reblooming Phalaenopsis is to give them a fall "chill" — expose them to dropping night temperatures as long as the temperature remains above 55 degrees. Also, when watering, do not let water sit in the crown of the plant.

Potted orchid: Pinus/Wikimedia Commons