Pink Lady’s Slippers (Cypripedium acaule), also known as Moccasin Flowers, differ from Yellow and Showy Lady’s Slippers in two fairly obvious ways. One is that the stalk the single flower is borne on bears no leaves. In addition, the pouch, or labellum, has a vertical slit running the length of it, rather than an oval opening on the top. Bumblebees are the only insect strong enough to push their way through this slit and are their main pollinators. In New England, almost 25% of the Pink Lady’s Slipper population have white flowers (see insert).
There are only about three short weeks in the late spring when the blossoms of Yellow Lady’s Slippers grace our woodlands and wetlands. The production of an orchid is a complicated process. If pollination and fertilization are successful, hundreds of thousands of some of the smallest seeds of any flowers are scattered by the wind. The seeds of Yellow Lady’s Slippers (and other orchids), unlike those of most flowering plants, contain no food for the seedling plant. In addition, the coating surrounding the seed is extremely tough, so much so that the seed can’t germinate until Rhizoctonia fungi digest the outer coating, which allows the inner seed to access soil nutrients. This can take two years or more and then it may take another few years for the plant to produce a flower.
Yellow lady’s slipper, Cypripedium pubescens, is in flower in central Vermont/New Hampshire, gracing woodlands and bogs with its beauty. This plant has what is called a mycorrhizal association, a relationship with a fungus that colonizes its roots. This mutually beneficial association provides the fungus with carbohydrates from its host plant, the yellow lady’s slipper, and enables the yellow lady’s slipper to have increased mineral absorption due to the fungus’s large surface area. More than 90 percent of plant species are believed to form a symbiotic arrangement with beneficial soil fungi.