Missouri Orchids

By Janice Wiese-Fales | April 1, 2020
From Missouri Conservationist: April 2020

Though you many not recall crossing paths with them on your treks into the wild, Missouri is home to more than 30 naturally occurring orchid species.

Orchids grow in specialized settings and bloom at specific times of the year. In some instances, you might not have recognized these plants’ diminutive blooms as orchids. For example, the adder’s mouth orchid appears in early summer in the Ozarks’ acidic soils, and at only 6 inches, is small enough to be easily overlooked. Mosquitoes, gnats, and midges pollinate its petite green blooms.

“Orchids are a jewel in any landscape,” said Peter Bernhardt, a professor of biology at St. Louis University, whose research includes pollination and breeding systems of flowers. “They’re always going to be kind of rare and an indication of a healthy landscape. Even jaded botanists get excited about them.”

In degraded ecosystems, orchids are among the first plants to disappear. Loss of habitat, collection by humans, pesticide and pollution interference, and climate change all play roles in reducing orchid numbers.

Slippers and Tresses

Two of Missouri’s most commonly occurring orchids are the spring-blooming yellow lady’s slipper and a handful of species in the fall-flowering Spiranthes genus, commonly known as ladies’ tresses.

“Yellow lady’s slipper orchids are very showy and not hard to find,” said Malissa Briggler, state botanist for MDC. “They grow in rich, moist woodlands throughout most of the state and flower in late April to early June.

“However, you don’t have to be in a pristine wild area to spy an orchid. Some species of ladies’ tresses can be found on roadsides,” she said, a nod to the species’ distribution in a wide variety of habitats throughout the state.

Yellow lady’s slipper orchids arguably are the most spectacular of our native orchids because of their blooms — inflated pouchlike lips, or slippers — that can measure up to 6 inches. Each 8- to 28-inch tall plant has a showy, nodding upper sepal and side petals that spiral downward as though styled with a curling iron, both with attractive brown-purple veining. They often grow in clumps of several plants. There also is a smaller variation of the yellow lady’s slipper with brown-maroon coloring. Both occur statewide.

Bill Summers noted in MDC’s Missouri Orchids, “a colony of lady’s slipper orchids in full bloom is a sight to be remembered always.” Hidden from above by foliage with a tendency to face downslope, he wrote, they are most easily located by looking upward from the bottom of a slope.

Two additional species of lady’s slippers grow in Missouri — the white lady’s slipper and the showy lady’s slipper with a rose-colored lip. A sighting of either is a rare luxury.

“Ladies’ tresses orchids, which occur in open fields where I live, are the most common Missouri orchid,” Bernhardt said.

All but one of Missouri’s seven species of ladies’ tresses orchids bloom in the fall with small white-to-yellowish trumpet-like flowers gracefully spiraling up the plants’ 6- to 20-inch stalks. Blooms on the various species are small, ranging from ¼ to 1 inch. Close inspection reveals each to have an ornately hooded and ruffled lip.

What Makes an Orchid?

One of the largest and most intricately evolved plant families in the world, every orchid has a dorsal and two lateral or side sepals — sort of modified petals. Each also features two side petals and a third known as the labellum, or lip. The latter is highly variable from species to species and nearly always points downward, serving as a landing pad for insect pollinators. Like the human face, orchid blooms have bilateral symmetry — if you draw a line down the flower’s center, the two sides perfectly mirror each other.

Orchid reproductive parts — the anther, stigma, and ovary — are housed in a single structure called the column. The male anther produces pollinia, masses of pollen grains that are transferred as a unit. The female stigma is a pollen receptor and the ovary contains unfertilized seeds called ovules.

Every orchid has coevolved with its own distinctive pollinators resulting in intricate reproduction adaptations that often are visually pleasing.

The inflated lip of the lady’s slipper orchid serves as a “trap” for treat-seeking bees that become sticky as they struggle to find their way out of the slipper, gathering pollen as they escape.

Missouri’s beautiful but rare grass pink orchids are “upside down,” with a fiddle-shaped lip at the top. A little tuft of orange-yellow hairs at the base of the lip mimics pollen, attracting bees whose weight forces the hinged lip to swing down, pressing pollen onto the reproductive column. Both native species’ blooms are striking — pink, butterflylike, and up to 2 inches — and occur in late spring in a variety of settings.

Many orchids have a hole at the base of the lip, leading to a tubular spur filled with nectar. Such is the case with Missouri’s showy orchis, a purple flowered orchid with a spade-shaped white lip. As the pollinator probes the spur for nectar, pollinia attach to it and are carried to the next orchid. Pollinated by bumblebees, the showy orchis is a woodland species that blooms in early spring.

Orchids produce thousands of dustlike seeds distributed by wind. The minute seeds carry no nutrition for their tiny embryos and rely on fungi found in soil to provide the necessary energy for germination.

Fungi that form these complex and beneficial relationships are known as
mycorrhizae. They pass nutrients to the embryo through tiny threads — hyphae — that penetrate the seed. As the embryo grows, it forms a protocorm with fine hairs that take nutrients from the fungus until the plant is ready to begin photosynthesis.

“It’s a difficult procedure to reestablish or transplant orchids because of the delicate mycorrhizal relationship,” said Briggler. “Attempts to relocate them are often unsuccessful. We don’t want to love them to death by moving them from wild habitats to flowerbeds.”

Look! Don’t Gather

Some orchids never lose reliance on the symbiotic mycorrhizal connection. Such is the case with Missouri’s two coral root species, one that blooms in the spring and one in fall. The crested coral root orchid blooms from July to September. A woodland species with multiple blooms on naked purple, reddish, or yellow 2- to 30-inch stems, these orchids occur in small colonies. The rare crested coral root’s bloom, though small, is quite spectacular with a three-lobed, white and purple lip.

Prairie Fringed Orchid

“We don’t track all of Missouri’s orchids, but the prairie fringed orchid is federally threatened, so we monitor its progress. We tend to know more about them because of that,” said Steve Buback, a natural history biologist with MDC.

Similar in appearance, two species of prairie fringed orchids naturally occur on Missouri’s prairies. As prairies diminished, so did the orchids that made their homes there. The eastern prairie fringed orchid was considered extirpated, or totally absent, from the state until it was rediscovered in 2009 growing in a small cemetery on a prairie remnant.

Growing from 1 to 3 feet, both species have numerous creamy white colored flowers with petals that form a hood over the column. The lip of both is deeply fringed, with three distinct lobes and a long thin nectar spur. The western species’ flower is larger; both are sweetly scented.

“Prairie fringed orchids have a tenuous life. It might take them three or four years to send up a leaf and five to seven years before they have enough resources to bloom,” Buback said.

“We learned of one stand of western prairie fringed orchids from a farmer who had never plowed a portion of his land because he made a bouquet of the orchids that bloomed there for his wife every year, which, oddly enough, led to long-term conservation.”

In the early 1990s, Dave Ashley, a now-retired biology professor at Missouri Western State University in St. Joseph, was approached by Dennis Figg, the then-MDC endangered species coordinator, about doing a count of western prairie fringed orchids in the area.

Originally skeptical, Ashley was setting insect traps on prairie lands with students and came across a stand of the orchids.

“I was pretty excited. I contacted Dennis and started monitoring them,” Ashley said. “In the beginning, my ultimate goal was to provide information about pollinators.”

Hawk moths hover over prairie orchid flowers, probe nectar spurs, and fly away. Ashley and his students tracked flower visitations using fluorescent powders and black lights.

“By directly observing flowers at night and using light traps and pollinator traps, we were able to find 15 to 20 different hawk moth species on the prairies,” said Ashley. “We knew how long the moths’ proboscises [elongated mouth parts that work like straws] were, and we matched them to the orchid spur length and could eliminate some species as pollinators.

“When the moth extended its proboscis all the way in, it hit its head on the flower and we could see the flower move back and forth. The sticky pollen packets would stick to its head, and it would move to the next flower.”

Ashley said that in addition to studying and caring for the prairie where these orchids grow, it is important to remember that larval stages of these pollinators and others are dependent on plant species that grow on the edges of prairies.

“It’s not just a matter of maintaining the prairie proper, but the landscape around it.”

Ashley said his work with the prairie fringed orchid pollinators and the ability to gather and share information about a species of concern may be as fulfilling as anything he’s ever done.

To date, Tom Nagle, retired MDC natural history biologist; Paul McKenzie, retired U.S. Fish and Wildlife Service endangered species coordinator; Buback and Ashley have identified five stands of western prairie fringed orchids.

“I took my wife to the prairie one night to help me monitor pollinator activity,” Ashley said. “We set up our lawn chairs and put on our headlamps. At dusk she said, ‘What is that sweet smell?’ I told her that fringed orchids do not waste their fragrance during the day. They save it for the hawk moths at night.

“Sitting on the prairie in the moonlight and realizing all that is in play is really exciting.”

This story does not cover every member of the Orchidacae family that makes itself at home in Missouri. The North American Orchid Conservation Center website is searchable by orchid species and allows for state-specific searches of all native orchids at goorchids.northamericanorchidcenter.org.

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