by Caroline Grass
August 01, 2022
The pink lady’s slipper is one of the largest native orchids in the United States and grows in forested areas in the eastern half of the U.S. and throughout most of Canada. They do well in shady areas with acidic soil, but need a fungus present in the soil before they can grow.
Because of the specialized growing conditions this flower requires, the pink lady’s slipper is not a common sight, but if you stumble upon an area that checks all the boxes of this flower's growing needs, you may just see a colony of this unique, pink orchid growing in the woods.
Relationships between organisms that increase chances of survival in the wild are common. Over 90% of land plants are thought to form mycorrhizal relationships with fungi, which is when fungal tissue and a plant's root tissue combine to help the plant grow. The pink lady’s slipper is no exception and forms this symbiotic relationship with fungi of the Rhizoctonia genus. The relationship is mutualistic (meaning both organisms benefit) and is a characteristic of almost all orchid species.
Unlike most plants, the seed of the pink lady’s slipper does not have a food reserve to help the plant grow before it can photosynthesize and produce its own food. Instead, the fungus will make nutrients available for the plant to absorb by breaking open the seed and growing into the plant's roots.
In return, the fungus is able to stay moist from the water-rich root environment of the plant and receives nutrients back from the pink lady’s slipper through its roots once the plant becomes photosynthetic and produces its own food.
While the pink lady’s slipper has a mutually beneficial relationship with fungus, it doesn’t show pollinators the same love. In fact, the plant essentially tricks bees into pollinating it without providing any nectar. The orchid will attract bees with its pink color and sweet scent, but once the bee enters the flower pouch through the front slit, the bulb shape and inward turned petals trap it. The bee will find it cannot exit the way it entered and will have to move through the flower to get out.
To exit through a different part of the pink lady’s slipper, the bee will rub against the stigma of the flower which is part of the female reproductive system. Any pollen the bee is carrying from other flowers will rub off and pollinate the pink lady’s slipper. The bees will soon learn that this flower does not provide any nectar for them as a reward and will avoid the flower.
The pink lady’s slipper takes years to mature but if left undisturbed, this remarkable flower can live for over 20 years! Through the years, the conservation status of this unique orchid has fluctuated from endangered, threatened and sometimes given a “special concern” status, but it is now considered secure in most areas.
The pink lady’s slipper is a beautiful plant to spot in the woods and if you see one, take a minute to admire the complex relationships the flower creates between organisms to survive.