Commonly called moth orchids, Phalaenopsis are popular house plants that will flower repeatedly once per year with the flowers lasting for four months or more with proper care. Phalaenopsis orchids are one of the longest blooming orchid genera.
Where do they come from?
Phalaenopsis are a class of around 45 species of mainly epiphytic orchids—orchids that grow on other plants— native to India, southern China, and Southeast Asia. Because these flowers are native to Southeast Asia, they are pollinated by Southeast Asian insects not native to the US, such as large carpenter bees in the genus Xylocopa.
What do they look like?
The showy flattened flowers appear in long bunches on arching stems in a range of colors including white, cream, light yellow and purple-pink. Plants of some varieties will grow to as much as 3 feet tall when in bloom with large leathery succulent leaves coming directly from the rootstock. They are mostly grow on trunks and branches of trees without taking water or nourishment from them. However, sometimes they grow on rocks taking nourishment from the atmosphere. They have a monopodial growth habit and lack pseudobulbs. Many of the roughly 70 species of orchids of the genus Phalaenopsis are called ‘moth orchids’ as a common name. Though there are some plants that are primarily moth pollinated, the name moth orchid is a reference to how their wide flat petals resemble a moth, and not what insects pollinate them.
How do they pollinate?
For Phalaenopsis orchids large carpenter bees are one of the most commonly seen pollinators. These carpenter bees are often met with anger (or pesticides) by homeowners. However, there is a complex and often unseen chain of interactions that happen between plant and insect species, with each native species playing a role. Most pollinators such as bees and butterflies visit flowers to get food in the form of nectar. Some also collect the protein-rich pollen, and as they go from flower to flower, some pollen is inevitably exchanged between plants and the flower becomes fertilized and can bear seed.
Some Phalaenopsis orchids have a sneaky trick. Everything about their flowers broadcasts to prospective pollinators that there is a tasty treat waiting for them in the flowers. They have nectar guides in the UV light spectrum that point to the nectar present in the center of the flower. They have similar shape, color and scent to other nectar producing flowers, but once bees push past the pollen producing parts of the flower they find out there is no nectar for them to feed on. Undeterred many bees will still investigate other nearby flowers and in the process the orchids become cross-pollinated. Some orchids so closely mimic the flowers of other endemic plant species that bees cannot tell them apart. Some orchids have evolved to target very specific groups of insects, or even a single species, for pollination and rely on them for survival.
Phalaenopsis at the Garden
The Garden has a long history with orchids. The first orchid specimens were given to Henry Shaw in the early 1870s by Mrs. Henry T. Blow. Her collection was the result of plants collected in Brazil by her husband while he served as Minister to Brazil under President Grant. The collection grew steadily until 1918, when the largest public display of orchids ever held in St. Louis was made at the Christmas Show.
Today, the Missouri Botanical Garden’s orchid collection represents one of the largest and finest in the United States. The garden has approximately 6,500 orchid plants, representing 686 unique taxa. There are a total of 2,179 plants that are species. The remainder of the collection consists of 1,438 cultivated hybrids. Visitors can see these orchids in the Climatron and in the Garden’s annual Orchid Show, held in the in the Emerson Conservatory in the Jack C. Taylor Visitor Center.
The Garden has are more than 400 Phalaenopsis in its collection, including 11 in the Climatron. The oldest Palaenopsis pulcherrima is 50 years old and was received in 1973. Roughly 15 phalaenopsis are displayed in the Orchid Show at any given time. Orchids are rotated into the show as they come into bloom.
Caring for a Phalaenopsis at Home
Phalaenopsis are one of the easiest and inexpensive orchids to grow in the home. It serves as an excellent houseplant as long as basic growing conditions can be met. Phalaenopsis grow in pots with a coarse fir bark potting mix that facilitates circulation of air, water, and superior drainage. Phalaenopsis prefer warm, humid, damp conditions, in temperatures ranging from at 72-85°F in daytime and above 60°F at night. Plants will tolerate some brief temperature extremes, but temperatures in excess of 95°F or below 55°F should be avoided. Best sites are on east window sills, but plants also grow well on well shaded sills with no direct sun. As the flower spike grows vertically, you will need to stake it for support. It is very tender and will break easily. As the buds and flowers develop, the stake will also carry their weight.
Aaliyah Butler, Public Information Coordinator