Most people are unaware of the sex and murder that goes on in the bogs of Manitoba as plants fight for survival in that nutrient-poor environment.
Both carnivorous plants and orchids are highly specialized and have very specific habitat requirements. Wetland drainage and global warming threaten their existence.
Carnivorous plants and orchids often use similar colours, scent and deceptive traps to seduce insects, but for different reasons: the orchids to get help with their sex life (pollination), and the carnivorous plants to kill and eat them for the nitrogen they need, sometimes using them as a pollinator first. This may be a kind of convergent evolution that took place when these two plant families evolved in the same harsh environment and were subjected to the same selective pressures.
Manitoba is home to 10 species of carnivorous plants that specialize in trapping insects for food. Here are just three of these species:
Purple Pitcher Plants (Sarracenia purpurea)
The leaf traps of the plants are shaped like a partially blown-up balloon with an attached wing and a hood-shaped flap at the top. They hold rainwater like a pitcher. Insects are attracted to the sweet nectar found on the ruffled collar of the leaf.
The collar and throat of the pitcher are covered with purple veins and bristly, downward-pointing hairs. When an insect lands on the collar, it eats the nectar and goes down into the leaf to get more. The inside of the leaf is very slippery lower down, and the insect soon slips and falls into the liquid and drowns. The leaf cells produce digestive juices and the insect's tissues are broken down and absorbed.
The leaves open to form a trap after the plant has finished blooming and the drooping red flower petals fall off, leaving only the large red style and the ovary. This means the early bee pollinators do not get trapped and eaten unlike unfortunate late-season wasps.
Round-leaved Sundew (Drosera rotundifolia)
These beautiful but deadly plants have sparkling droplets of clear nectar clinging to the pinkish tentacles of their leaves. An insect is attracted to the aroma and the nectar and lands on the leaf. It immediately becomes trapped in the sticky fluid and, as it struggles, it triggers the production of more sticky fluid and causes the tentacles to curl around it. The plant secretes strong digestive juices and the insect is absorbed.
The sundew has a single white flower that blooms when the leaf traps are open and, as a result, the same insects that serve as pollinators are often trapped by the leaves and eaten afterwards.
Common Butterwort (Pinguicula vulgaris)
This unusual plant has two kinds of glands on its leaves; one produces oily glue and the other a strong acid. When an insect is attracted by the musty smell of the leaves and the violet colour of the flower, it pollinates the flower and then visits the rosette of leaves at the base of the plant. The leaves immediately secrete a large amount of oily glue, which covers the insect's breathing holes, and it suffocates. The leaves secrete a powerful acid and the insect is absorbed by the ungrateful plant.
Manitoba also has 37 species of native orchids. Orchids specialize in attracting pollinators by modifying one of their petals, called the lip, to be especially attractive to a specific kind of insect. Here are two species of rare wetland orchids that also use gorgeous shapes, colours and deceptive methods to attract insects.
Dragon's mouth orchid (Arethusa bulbosa)
The showy rose-purple colour of the flower reminds one of its pitcher plant companion. While it produces no nectar, the delicately scented flower with its ruffled lip is so beautiful that the bee pollinator cannot resist it. Both these plants are pollinated by bees, both have a sweet scent and their deceptive lures ensure the pollinator gets nothing in the end (or worse).
Grass Pink orchid (Calopogon tuberosus
These orchids, like sundews, are a seductive pink colour and use a deceptive trap to ensure pollination. The hinged lip on this orchid is uppermost and is covered with bright yellow hairs that are very attractive to bees. When a bee lands, the lip suddenly bends down and snaps closed, throwing the bee on its back onto the sticky column where it deposits pollen on the stigma. As the bee struggles out, it picks up pollen to be deposited on the next flower. The bee gets nothing but a rough ride!
If this article has interested you in knowing more, I recommend you read Savage Garden by Peter D'Amato. and Orchids of Manitoba by Ames et al. For a list of plant suppliers, or if you'd like to join me on a field trip to see these rare carnivorous plants and native orchids in their wetland habitat, visit the Native Orchid Conservation Inc. website at www.nativeorchid.org.
Doris Ames has served as president of Native Orchid Conservation Inc. since 2002 and is in charge of project management at the Brokenhead Wetlands. She also collects seeds from native orchid species for long-term storage in the National Gene Bank in Saskatoon.
