Common Name: Pink Lady’s Slipper, Moccasin flower, Venus’s shoes, Nerve root, American valerian – The sack-like distension of the lower, pink petal is similar to the shape of a rounded shoe, such as a slipper or a moccasin.
Scientific Name: Cypripedium acaule – The generic name derives from the Roman name for Venus which is Cypris (who mythologically arose from sea foam off the coast of Cyprus), and the Latin pedium, which means sandal; literally then, the generic name translates as “Venus’s sandal.” Botanists in the middle Ages named the flower Calceolus marianus, the “little shoe of the Virgin Mary.” The species name acaule is Latin for ‘without a stalk (caulis),’ as the flower grows directly from the basal leaves without a true stem.
Potpourri: The lady’s slippers of the genus Cypripedium are among the most extravagant and recognizable exemplars of the Orchid family; they inspire wistful encomiums whenever they are encountered. There are about 50 species in the genus of these perennial, terrestrial orchids that are found throughout the northern hemisphere in both Eurasia and North America. The daintiness and delicacy of the ornament-like saccate flower belies their hardiness; lady’s slippers flourish in habitats that range from above the Arctic Circle in Alaska to just north of the Equator in Central America – one species is found in the Himalayas at an elevation of 4900 meters. There are twelve species in North America; C. acaule, the pink lady’s slipper and C. parviflorum (sometimes C. pubescens), the yellow lady’s slipper are the most common in the middle Appalachian regions. There are some rather unusual features about the cypripedia in general and about the pink lady’s slipper in particular that make them distinctive, even for orchids, which are noted for their eccentricity among the flowering plants.
It was Charles Darwin who first elevated the orchids to the notice of Western European science. In his prescient On the Various Contrivances by which British and Foreign Orchids are Fertilized by Insects written in 1862 (shortly after the publication of On the Origin of Species), he noted that orchids were uniquely evolved to attract very specific insects for pollination: “In my examination of orchids, hardly any fact has so much struck me as the endless diversity of structure … for gaining the very same end, namely, the fertilization of one flower by the pollen of another.” The experiments, which involved covering some flowers with glass bells to prevent access, demonstrated that only the uncovered plants achieved fertilization viability. This served as the basis for the postulate that the transfer of pollen from one flower to another was the key to evolutionary diversification.
Orchids are characterized by three distinctive features: three petals; three sepals (comprising the calyx which is the outer sheath of the flower bud); and a specialized columnar reproductive organ that combines the male and female reproductive organs (stamens and pistils respectively) into one structure. The success of this arrangement is evident in their ubiquity; there are about 20,000 species of orchid globally, second in size only to the composite Asteraceae family of daisies and sunflowers. The reason is that, for the most part, each orchid is matched in structure to attract a specific pollinator. The pink lady’s slipper, C. acaule, is pollinated primarily by bumblebees (Bombus vagans) and the yellow lady’s slipper, C. parviflorum, is pollinated by carpenter bees (Ceratina calcarata). The lowest of the three petals, known as the lip or more properly the labellum, is typically asymmetrically positioned at the opening like a landing pad for the insect, which is the right size and shape to fit into the aperture in search of the source of the aroma that therein emanates. The pollen is situated at the front of the column and is affixed to sticky membranous material that ensures adherence to the pollinator as it passes; a second membrane prevents the insect from proceeding further to preclude self-pollination. The deception of the orchid is even more insidious, as it produces absolutely no nectar as a reward to the dutiful insect; the attraction is entirely olfactory from a complex chemical mix that includes acetates, terpenes, or compounds that have aromatic benzene rings. It is thought by some scientists (though not yet confirmed) that the scent of at least some orchids is matched to the sexual pheromone of the targeted pollinator – the attracted insect is duped into providing for the orchid’s sexual needs while anticipating its own in one of nature’s more compelling ironies. The pink lady’s slipper extends the manipulation one step beyond the olfactory; the bumblebee pollinator can only go in one direction. The pouch-like labellum has an orifice only at the very top through which the insect must pass to gain access. The margin of the orifice is folded inward so that once inside, the only egress is afforded by climbing up the interior portion of the saccate bulb and out an opening in the back, conveniently passing by the anthers to collect pollen along the way.
Orchids have a very close affiliation with the kingdom Fungi; they cannot survive in isolation. The reason for the obligate dependence of orchids on fungi is that orchids do not invest a great deal of energy in their production of seeds; orchid seeds lack a protective coating called an aril and they have no endosperm, the fuel for seedling growth. While this makes them very light to promote wind and water dispersal, it does not allow for autonomous germination as there are no nutrients for the embryonic seedling to consume; that nutrition must then be provided by fungi. According to Bryce Kendrick in The Fifth Kingdom, “For the first two to eleven years of their lives – until their first chlorophyll-bearing leaf develops – these plants depend on being colonized by fungi, commonly basidiomycetous anamorphs of the genus Rhizoctonia.” Since this is a very common saprophyte (consumes dead matter) in soil, the success of the orchid seed is not all that unusual. However, there are many types of fungi in the soil and it is not necessarily the case that compatibility will prevail; quite frequently a non-compatible parasitic fungus kills the seedling. There is some evidence that the pink lady’s slipper extends this mycological dependency into adulthood, throughout its estimated 30 year maximum lifespan, a remarkable longevity for a flower. The basis for this supposition is that, unlike most other orchids, C. acaule goes into dormancy for years at a time, producing no hypogeal, chlorophyll-producing parts with which to maintain nutritional viability. There is really not that much that is new about the close relationship between orchids and fungi – about 90 percent of all plants have a mutualistic association with fungi that is known as mycorrhizal (Latin for fungus root which is where the nutrient transfer occurs). However, only the orchids rely on the fungi for incipience and, so far as is currently known, only the Pink Lady’s Slipper relies on the fungi completely during a portion of their normal life cycle. This may be in part due to the fact that the cypripedia have been found to be associated with a particular fungal group. In the February 2005 Journal of Molecular Ecology, Shefferson et al, reported in “High specificity generally characterizes mycorrhizal association in rare lady’s slipper orchids, genus Cypripedium” that they “associate with generally unnamed members of the fungal family Tulasnellaceae,” which are widely distributed soil fungi. This research is at the leading edge of our understanding of the many complex relationships between the Kingdoms Plantae and Fungi.
Orchids undoubtedly captured the imagination of humanity consequent to the first glimmerings of art and beauty manifest in prehistoric cave drawings and decorative artifacts. The earliest records that mark the vestigial mists of cultural growth, such as the writings of Confucius in the fifth century BCE, are evidence of this. Lan was the Chinese term for the fragrance of orchids which became Ran in Japanese and extended beyond fragrance to nobility. In Greek Mythology, the orchid rose to uses beyond the aesthetic to the analgesic. Orchis is the Greek word for testicle; the association arises from the ovoid shape of the orchid bulb. The priapic leitmotif extended to the notion that orchids arose from the semen of goat-men called satyrs and consequently to an appropriate mythological story line, Orchis anthropomorphized as a misbegotten son of a nymph and a satyr. His heightened passions an obvious result of this union were his downfall in the seduction of a priestess after a bacchanal. He was literally torn asunder by the populace who scattered the pieces to satiate their evident rage; his satyr father convinced the gods to allow a flower to grow from his remnants and thus the orchid arose as “teste – monial”. The notion of the orchid bulb as medicinal began with its use as an aphrodisiac, the obvious extension of its satyr – nymph sexual provenance. The Greek physician and pharmacologist Dioscorides set the precedent in the seminal (pun intended) De Materia Medica in about 60 CE in his assertion that eating large orchid bulbs would result in male offspring while small bulbs would yield females. With the intervention of the Dark Ages and the ensuing feudal period, it was not until after the Renaissance that art and science again flourished in Western culture, and John Gerard, the noted English herbalist, resurrected the orchid in his Generall Historie of Plantes in 1597, promoting the consumption of “dogs’ stones” for “fleshy lust.” Things were a little different in the New World, where the customs of Europe merged with the medicines of the Native Americans.
The yellow lady’s slipper (C. parviflorum) has been a staple of the Native American “nature pharmacopoeia” for millennia, quite independent of any organoleptic association; the common name ‘moccasin flower’ is likely an etymological carryover. As the diverse tribes had independent origins, their uses were the result of individual shamanistic experimentation. The Cherokees made a root ptisan to treat worms, the Iroquois made a tonic that was used as a sedative; there were many other applications that ranged from irritable bowel syndrome to postpartum pain depending on local traditions. The colonists, being Victorian on the one hand and in need of medicines in the harsh New World on the other, had no interest in the orchids as cantharides but sought out their reputed cures from their indigenous neighbors (when relations allowed). Consequently, orchid bulb gathering became widespread, so much so that the noted autodidact naturalist Constantine Rafinesque noted in 1828 that the orchid rhizomes were “collected in the fall … carefully dried and reduced to a powder.” The common name “American Valerian” is a direct result, as valerian (Valeriana officinalis) has long been used in Europe as an herbal medicine. Since the yellow lady’s slipper was noted to be the more potent than the pink lady’s slipper, it was collected much more assiduously, a fact that has most likely resulted in its relative scarcity; one finds mostly pinks. There has been recent concern that the encroachment of human habitat would threaten the orchids in addition to their continued depredation for medicinal use and the (almost always unsuccessful) relocation of mature plants to suburban gardens. The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) lists all Cypripedium species in Appendix II, i.e. not necessarily threatened with extinction at this time, they may become so if trade is not restricted.
Laboratory analysis of the orchid bulb has confirmed a chemical cornucopia that includes phenolics, alkaloids and several quinones named for the lady’s slipper Cypripedium genus: cypripedine, and cypritibetquinone A and B. As most of these groups contain specific compounds that have some pharmacological associations, it is reasonable to conclude that the use of yellow lady’s slipper for the treatment of various afflictions was valid, and not an example of 19th Century “snake oil” medication. The general procedure was to grind the rhizomes to a powder and add five tablespoons in one pint of boiling water for one hour (to remove volatile compounds that would likely be iatrogenic if consumed). The recommended dosage of one teaspoon per hour was most frequently prescribed as a sedative or nerve tonic. However, there were many other uses, some probably more placebo than palliative. The Peterson Medicinal Plants and Herbs Field Guide provides that yellow lady’s slippers were used in 19th Century North America “as a sedative for nervous headaches, hysteria, insomnia, nervous irritability, mental depression from sexual abuse, and menstrual irregularities accompanied by despondency (PMS?).” It is fortunate that the use of lady’s slippers as a source of psycho-pharmaceuticals has fallen into desuetude and that they have remained the delicate forest sentinels of yore, even though the conditions for which they were prescribed have become more prevalent in the hot, flat, crowded and frenetic 21st Century. Another good reason to seek the sanctity of the woods.