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| The pink lady's slipper. |
Any successful business venture is liable to attract cheats and con artists. Nature certainly has its share of these. The rare flower known as the lady's slipper is one of them.
In order to understand the wily ways of the lady’s slipper, one must first know a thing or two about plant reproduction. Plants can reproduce when a pollen grain from one plant unites with an egg from another plant of the same species. This fertilized egg develops into a seed, which then grows into a plant.
But if plants are stationary, how do the pollen and the eggs meet? In some cases, they rely on the wind. A plant will release its pollen into the air, letting the wind carry it to other plants. In other cases, plants enlist the aid of bees and other insects to transport their pollen.
This is supposed to be an equal partnership, working to the benefit of both parties. The insects pollinate the flowers, and in return, the flowers supply the insects with a source of food in the form of nectar.
For the last few hundred thousand years, insects and flowers have been perfecting this relationship. Today, they are dependent on each other. If insects were to disappear, half the plants on earth, including many that we rely on for food, would quickly become extinct.
How does this pollination scheme work? What makes the insect want to pollinate the flower?
A plant attracts an insect -- we’ll use the bee as an example -- by producing nectar, a sweet-smelling concentrated sugar solution. You can find out what nectar tastes like by finding a head of clover, pulling out an individual flower, putting the small end in your mouth, and sipping it as if it were a straw.
As the bee feeds on the nectar, it rubs against the plant’s pollen, which sticks to its body. The bee can use this pollen for food, but as it moves from flower to flower, some of the pollen falls off. In this way, the pollen is transported from one flower to another, where it may fertilize an egg.
The pink lady’s slipper, often found in the woodlands of the South Shore, is one of the many flowers pollinated in this manner. The work is done primarily by an insect known as the solitary bee.
Unlike the honeybee and the bumblebee, the solitary bee is . . . solitary. It lives alone. Each bee is a queen in her own right, but a queen without a court. She must construct her own nest, provision it with food, lay an egg, close up the nest and then start again.
The solitary bee is attracted to the sweet smell of the lady’s slipper, one of spring’s most lovely and delicate flowers. But there is more to this beauty than meets the eye. Excited by the prospect of a nectar meal, the bee forces its way into the bulbous flower. However, once inside, it discovers . . . no nectar! It has been tricked.
The bee then attempts to leave the lady’s slipper. A light patch at the bottom of the flower shows the bee the way out. Near the exit the bee must squeeze beneath the flower's anthers, where the pollen is produced. In exiting the flower, some of the pollen sticks to the bee, but not enough to justify such an effort. The bee must continue searching for food.
Now comes the amazing part. In order for this pollination scheme to work, the bee must be tricked into entering another lady's slipper. And it works!
As it travels through the next lady’s slipper, the bee brushes against the flower’s sticky stigma. Pollen from the first plant sticks to the stigma, which contains the eggs. The pollen from the first lady's slipper fertilizes the egg of the second lady's slipper, and seeds are produced.
Experiments have shown that bees quickly learn to avoid lady's slippers. Therefore this pollination scheme relies on young, inexperienced bees just emerging from their nests. Perhaps this is why lady's slippers are never very abundant in any one area.
Once the lady's slipper has been pollinated, it is time for the seeds to be spread. If the seeds were to just fall to the ground, there would be large numbers of lady's slippers in one spot, the bees would get wise, and many plants would go unfertilized.
To prevent this, the seeds of the lady's slipper are tiny. They are so small that they will be carried for long distances by the wind. This insures that the plants will be spread far and wide.
The lady’s slipper’s convoluted path of propagation does not end there. When the seeds land, they are not able to begin growing. Most other types of seeds carry enough food to sustain them until their leaves emerge and they can produce their own food, but because the lady’s slipper’s seeds are so small, they cannot carry this food supply. Again, they must rely on assistance from other species.
Help comes in the form of a fungus living in the soil, which invades the seeds’ root system. The roots begin digesting the fungus, where they find nourishment enough to grow. After a few years, the lady's slipper finally sends forth leaves and begins producing its own food.
The lady's slipper is an amazing flower. For it to survive, it must trick a bee . . . twice. Then it must disperse its seeds far and wide, and these seeds must land in soil with the right kind of fungus.
But the most amazing thing about the strange life of a lady's slipper is that this all happens with no conscious thought from the flower: it just happens!
by Don Salvatore & Kezia Bacon
North and South Rivers Watershed Association
May 1997
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