Updated: Apr 29, 2022
Everyone loves orchids. They are not very common and are widely appreciated for their delicate beauty. One orchid, the Great Plains Ladies'-Tresses, is having an exceptional year growing on the remnant prairies around La Crosse, including those in Hixon Forest. On recent prairie restoration work outings they have been seen in much greater numbers than in the past. These fluctuations are somewhat unpredictable and it is not completely known why this orchid is so prolific in some years but not others.
The scientific name is Spiranthes magnicorporum. Spiranthes describes the spiral pattern of the flowers as they ascend the flower stalk or raceme, and magnicorporum refers to its historic range across the prairies of the Great Plains. A tress, as in the common name, is a long lock of hair that is usually braided which the flower stalk is said to resemble. Here is a picture of the orchid on a bluff prairie in Hixon that is being restored by Friends of the Blufflands:
Orchids are very finicky about where they grow. Each species needs just the right amount of moisture and sunlight, the right soil constituents like calcium, and a narrow range of soil pH. Ladies'-Tresses prefer a less acidic soil like that on the bluff prairies buffered by the calcium carbonate in some of the rock layers. As in a previous blog post, "Entangled Prairie", they also need the right fungal partner to thrive, especially when just starting to grow from seed. Rarely will an orchid survive if dug up and removed from its natural microclimate and specific fungal partner and transplanted to a different location. Doing this is also illegal in most cases. Unfortunately, harvesting wild orchids has contributed significantly to the demise of several orchid species in the United States and throughout the world.
Great Plains Ladies'-Tresses grow up to 16 inches tall and bloom in September and October. It is a special concern plant in Wisconsin with a decreasing population mainly due to loss of habitat. It is one of 6 orchids in the genus Spiranthes that grow in Wisconsin and is differentiated from other species in the same genus, in part, by the lack of basal leaves when flowering and by a conspicuously pleasant odor said to smell like vanilla. In fact, some say that they can detect the plant by its odor even before seeing it buried in the taller plants of the prairie.
The flowers of orchids are admired by many for their exquisite form. The characteristic lip or labellum of orchids is the lower petal sometimes referred to as the landing pad for pollinators. The lip of the Ladies'-Tress labellum is white with a tinge of yellow and a frilly border. A white hood completes the flower structure along with two lateral sepals, that are white, look like petals, and spread up and out looking like small cow horns. Bumblebees are a primary pollinator of this and many other orchids. Maybe one of the rare Rusty Patched Bumblebees as described in a previous blog post pollinated some of the Ladies'-Tresses growing this year! Orchids avoid self pollination by an interesting sequence of events. When the first pollinator arrives at the flower the female part of the plant, the stigma, is hidden inside a structure called the column. As nectar is consumed, the pollinator is exposed to the pollen from the male part of the flower called the anther. Once it exits carrying off the pollen, the column lifts up, exposing the stigma for pollination by the next visitor seeking nectar. If that next visitor is carrying pollen and pollination is successful, small seed capsules are eventually produced that later send thousands of dust like seeds on a wind blown journey hoping to land in just the right spot to produce a new plant. If the seed gets lucky and finds the perfect spot, it often spends its first several years underground being nursed along by its fungal partner in what is called the mycorrhizal stage before finally growing above ground. Even after this stage, in unfavorable years the orchid may not grow above ground at all but rest quietly below the surface until a better year comes along. Once established these orchids can live up to 50 years.
Friends of the Blufflands continues the effort to restore the prairies in the surrounding bluffs to expand the habitat for these orchids and the many other plants and animals that call it home. Please consider joining us in our efforts by becoming a member or by making a donation.