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Sex and Murder in the Bog: Carnivorous Plants and Orchids

by Doris Ames

Similarities between Carnivorous Plants
and their Orchid Companions:

  • Both live in nutrient poor bogs and fens
  • Both are highly specialized
  • Both require very specific habitat
  • Both use similar colours and deceptive traps to lure insects
  • Both are beautiful and fascinating
CP01a: This presentation is unusual in that it features both carnivorous plants and orchids. But there are many similarities between carnivorous plants and those species of orchids that grow alongside them in nutrient-poor bogs and fens. Both seduce animals but for different reasons: the orchids to help them with their sex life, the carnivorous plants mainly to kill and eat them although sometimes they use them as a pollinator first. In the manner of psychopathic lovers these plants use their beauty, empty promises of reward, and sophisticated traps to lure, take advantage of, and kill their victims.

Carnivorous plants often use the same vivid colours as orchids and the same deceptive lures that provide no rewards and may even lead to death, in order to attract insects. This may be because of a kind of convergent evolution that took place when these plants evolved together in the same harsh environment and were subject to the same selective pressures. The carnivorous plants are believed to have evolved 60-120 million years ago, certainly after the flowering plants, but because their bodies are so soft and fleshy, very few remain in the fossil record. While orchids are one of the largest plant families with 25,000 species, the carnivorous-plant families are among the smallest with only about 600 species betrween them. Both orchids and carnivorous plants are highly specialized and their habitat requirements are very specific. Because their wetland habitat is disappearing very quickly many of the species in these families are becoming very rare. Wetland drainage and climate change are two of the greatest threats to their existence.

Manitoba is home to 10 species of carnivorous plants belonging to 4 different families:
CP01b: Pitcher-plants (Sarracenia)
CP02: Sundews (Drosera)
CP03: Butterwort (Pinguicula)
CP04: Bladderwort (Utricularia)

There are 10 species of carnivorous plants in Manitoba:

  1. Purple Pitcher-Plant (Sarracenia purpurea)
  2. Oblong-leaved Sundew (Drosera anglica)
  3. Slender-leaved Sundew (Drosera linearis)
  4. Round-leaved Sundew (Drosera rotundifolia)
  5. Small Butterwort (Pinguicula villosa)
  6. Common Butterwort (Pinguicula vulgaris)
  7. Horned Bladderwort (Utricularia cornuta)
  8. Flat-leaved Bladderwort (Utricularia intermedia)
  9. Lesser Bladderwort (Utricularia minor)
  10. Greater Bladderwort (Utricularia vulgaris)
CP05: Carnivorous plants are found in the nutrient-poor environment of bogs and fens and they lure and trap animals (usually insects) for food. They need the extra nitrogen to survive in that hostile environment. They are the only kinds of plants that lure and trap animals for food.

Trap-mechanisms in carnivorous plants are of 3 kinds:

  • Passive traps - e.g. pitcher-plant
  • Semi-active - e.g. butterwort and sundew
  • Active - e.g. bladderwort
CP06: Overview of Trap Mechanisms -- the passive water-filled traps of the pitcher-plants drown their victims, the semi-active or flypaper traps of the Sundews and Butterworts use movement as a supplement to adhesive, and the aquatic Bladderworts use active traps to catch their insect victims. Bladderwort traps have such fast reflex action that they seem more like an animal than a plant. Much of the movement of carnivorous plants remains unexplained. Unfortunately carnivorous plants are becoming rarer as the bogs and fens in which they live are disappearing. We need to protect them.

Purple Pitcher-Plant (Sarracenia purpurea)

  • Passive trap - no movement
  • Leaves open to form pitcher-shaped trap
  • The trap holds digestive liquid
  • Insect is attracted by nectar and red veins
  • Insect starts to go down inside the leaf to get nectar, slips and falls into the fluid
  • Downward-pointing hairs prevent escape
  • It drowns and is absorbed by the plant
CP07b: Purple Pitcher-plant Traps -- this peculiar plant doesn't use movement or glue to catch insects. It relies on the wonderful design of its leaves. The leaves open up to form a trap after the plant is finished flowering. The leaves are shaped like a partially blown-up balloon with a wing attached and a hood-shaped flap at the top. They hold water like a pitcher but in this case the liquid is really digestive juice. The insect is attracted by the smell of the sweet nectar found on the wing of the leaf and leading up to the mouth. It lands on the ruffled flap-like collar, which is covered with downward pointing bristly hairs. Once past the hairs it has to go back down because it can't go back up. The inside of the lip is very slippery and it soon loses its footing and falls into the liquid. The insect drowns in the digestive juices and is absorbed by the plant.

Sundews (Drosera)

  • Semi-active trap uses adhesive and movement
  • Glistening drops of clear sticky fluid on pink leaf tentacles
  • Insect attracted by the colour and aroma lands on the leaf and gets stuck
  • Movements trigger plant to produce more adhesive and digestive fluid
  • Leaf curls up round insect and it is absorbed
CP08b: Sundew Traps -- these delicate plants are the most beautiful of the carnivores. They use a combination of adhesive and movement to trap their prey. Drops of sticky fluid clinging to the pinkish tentacles on the leaves sparkle in the sunshine. An insect attracted by the colour and aroma of the plant lands on a leaf and becomes trapped in the sticky fluid. Its movements, as it struggles to break free, trigger the production of fluid and cause the tentacles to bend around it. The plant then secretes a powerful digestive fluid that liquefies the insect and absorbs it quickly.

Common Butterwort (Pinguicula)

  • Semi-active trap - scent and movement
  • 2 kinds of glands on the glistening leaf produce oily glue and acid
  • Insect attracted by glistening leaves and musty smell
  • Insect lands on a leaf and movement triggers plant to release more glue
  • When insect is trapped other glands produce acid and leaf curls inward
  • Insect is digested and absorbed by the leaf
CP09b: Butterwort Traps -- this unusual plant has two kinds of glands on its leaves. One kind produces oily glue and the other a strong acid. When an insect like a fungus gnat comes along, attracted by the colour and musty smell of the leaves, it lands on the rosette of leaves. The leaves immediately secrete large amounts of glue and it becomes entrapped. The plant then secretes digestive acids and quickly turns its body to mush. It is then digested and absorbed by the plant. Acid production in these kinds of plants is triggered by any object containing nitrogen so the plant can feed on seeds or pieces of leaf as well as insects. There is actually an antibiotic in the leaves that keeps trapped insects from decaying.

Bladderworts (Utricularia)

  • Active traps - movement only
  • Grow in water or peaty shores of lakes
  • Traps are tiny, round bladders on the stems
  • Traps have a door on one end with a partial vacuum inside
  • Tiny trigger hairs stick out of closed door
  • An insect swims past and touches the hairs
  • The door springs open and the insect is sucked in
  • The door snaps shut and the insect is digested and absorbed
  • The water is then pumped out and the trap is reset
CP14a: Bladderwort Traps -- the traps of the bladderwort are unique among carnivorous plants. Tiny, round bladders grow on the stems and the leaves. These bladders have an airtight door at one end. When the door is closed the bladder expels water through its walls leaving a partial vacuum inside. There are tiny trigger hairs sticking out of the door. When an insect like a mosquito larva comes swimming along and touches the hairs, the door springs open and it is sucked into the bladder trap by the vacuum. The door snaps shut in the blink of an eye and the plant pumps in digestive fluid and digests and absorbs the insect. Then the water is pumped out and the trap is reset.
CP14b: Bladderwort Traps
CP14c: Bladderwort Traps
CP15: Pitcher-plant with bud -- Manitoba has one species of Pitcher-plant called Purple Pitcher-plant or Sarracenia purpurea.
CP16a: Pitcher-plant Flower with long red petals
CP16b: Pitcher-plant Flower with pink petals
CP16c: Pitcher-plant Flower petals close-up
CP16d: Pitcher-plant Flower bud opening out
CP17: Pitcher-plant Flower deep red
CP18: Pitcher-plant leaf with water
CP19: Pitcher-plant leaf showing hairs and veins -- These plants eat mosquitoes, midges, flies, and wasps to get the NPK they need. A saprophytic fly larva actually lives in the leaf pitcher and eats the left-over insect body parts. The pollinators are bees and the pitcher-plant does not eat them. The leaves open up and form the trap after the plant has flowered and the petals have fallen away leaving only the brightly coloured sepals. The Cree regarded Pitcher-plants as special and used the dried plant in combination with other herbs to treat smallpox victims.
CP20: Purple Pitcher-plant seed-head -- the plant produces thousands of dust-like seeds. Late last fall I saw pitcher-plants in a bog east of pr#308 with their leaves stuffed with dead wasps.
CP21a: Sundew plant
CP21b: Sundew leaf close up -- Some flowers may self-pollinate but most sundews rely on midges, mosquitoes, and gnats, the same insects they use for food. They were considered love charms by the Kwakiutl Indians and said to be especially effective on women!
CP22: Oblong-leaved Sundew (Drosera anglica) with white flowers
CP23a: Oblong-leaved Sundew (Drosera anglica) -- They have long skinny leaves that react to a trapped insect's struggles by curling up around it.
CP23b: Butterwort Plants can trap ants, mosquitoes and midges on their sticky leaves.
CP24: Butterwort Plants can trap ants, mosquitoes and midges on their sticky leaves.
CP25: Butterwort buds and leaves -- these same insects are the pollinators and after carrying the pollen from one flower to another they can be caught in the leaf trap and eaten.
CP26a: Butterwort close-up leaf -- Butterwort leaves are rubbed on the open sores of animals in Scandinavia to help them heal faster and they are also used as a milk coagulant.
CP27a: Bladderwort plant -- Bladderworts are very highly developed plants that live in or near water. They are the largest of the carnivorous plant families and are found almost everywhere.
CP27b: Bladderwort flower -- Although Manitoba bladderwort flowers are yellow they come in many beautiful colours in other parts of the world and some flowers can be as big as a medium-sized butterfly. Bladderworts are completely rootless and propagate mainly by vegetative means. There are buds that form at the tip of the floating stems. These fall off in autumn and sink down into the mud. Bladderworts eat worms, water fleas and mosquito larvae.
CP28: Venus Fly Trap (Dionaea muscipula) -- Venus Fly Traps grow only in the United States, and only in North and South Carolina, but they are the carnivorous plant that most of us identify with. In their natural habitat they mostly eat ants so they should possibly have been called Venus Ant traps. Their active leaf traps are extremely interesting. Insects are attracted to the red colour and scent of the leaf rosette. In the inside of each leaf on either side of the trap there are 3 extremely sensitive trigger hairs. When an insect touches a trigger hair once nothing happens. This means nothing happens if a leaf or something falls on it. However when the prey brushes against a trigger hair again the leaf snaps shut. The "teeth" interlock and enfold the victim. Small insects can crawl out between the teeth but when larger ones struggle they repeatedly trigger the hairs and the trap snaps closed squeezing the insect tight. Then the trap fills with liquid and the insect drowns. The digestive liquid breaks down the insect's body and it is absorbed by the plant. In a few days the leaf opens, the insect skeleton blows away and the trap is reset.
CP29: Venus Fly Traps are nearly extinct in the wild because people keep digging them up. When I saw them growing in the sandy soils of North Carolina's longleaf pine savannas there were more holes than plants.
CP30: Yellow Trumpet Plant (Sarracenia flava) clump -- Another very striking species found in Green Swamp area of North Carolina. The trumpet-shaped pitchers are 2-3 feet tall and a bright yellow or green colour. The flower petals are bright yellow. The trumpet-like leaves have a large almost horizontal lid that flying insects like to land on.
CP31a: Crawling insects like the beautiful but poisonous lynx spider follow the red veins up to the top of the pitcher The insects get drunk with the smell of the flowers and fall down into the narrow pitcher. The sides are waxy and smooth and there are downward-pointing hairs near the bottom. Digestive liquid rises up as the insect struggles and they drown and are digested by the plant. Flies, ants, bees and wasps are the usual victims but not the Lynx spider. It hangs around trying to catch the insects on the pitcher lid before they fall in.
CP31b: Yellow Trumpet Plant leaf
CP32: Yellow Trumpet Plant flower
CP33: I also saw some sundews that we don't have here; the Pink Sundew (Drosera capillaris) with a large rosette of spoon-shaped leaves and a pink flower.
CP34: Drosera filiaris
CP35: Drosera intermedia -- a temperate sundew that is semi-aquatic usually growing around lakes or in ditches in several inches of water. The whole plant is a striking maroon colour.
CP36: a rare variety of Hooded Pitcher-plant (Sarracenia minor) leaves -- The lid forms a hood over reddish leaves and there are light windows on the upper back of the leaves. Insects are led to the trap by the nectar trails and when they reach the top they are in a darkened space because of the overhanging lid. They see the light from the "windows and crawl towards it thinking it is an escape hatch but the sides are slippery and they fall into the digestive liquid at the bottom and drown. Ants are their favourite prey.
CP37a: Flowers Sarracenia minor
CP37b: Another very interesting carnivorous plant is Nepenthes or Monkey Cups with about 70 known species. I think this might be Nepenthes alata, red form. It is found in the mountainous jungles of southeast Asia growing as a long vine that clambers up through the trees or along the ground. The full-grown plants are up to 500 feet long with large simple flat leaves tipped with a tendril. The tendril is an extension of the mid vein and a cup forms on it. The large pouch-like pitcher extends from one or more leaf tendrils. These colourful pitchers can hold from 1/2 pint to several quarts of liquid depending on the species and large ones are supported by the tendril wrapping itself around the trunk of the tree. When insects lean over the lip of the trap to get at the nectar they usually fall in and drown. When flying insects land on the water their wings get wet and they too become food for the plant.
CP37c: Nepenthes burbidgeae
CP37d: Nepenthes burbidgeae close-up pouch with fluid
CP37e: Nepenthes alata leaves with tendrils -- The pitchers are sometimes large enough to catch large rats and folklore has it that the liquid in the pitcher-like trap can cause rain and prevent bedwetting. According to Malaysia folklore monkeys drink the liquid in the pods to make their voices sweet when courting. The clear liquid is said to be sterile but somehow I am not keen to try it. Apparently ground-dwelling Nepenthes in Malaysia are evolving to digest plant detritus rather than insects for their nutritional requirements.
CP38: Dragon's Mouth (Arethusa bulbosa) -- Now we come to the orchids that live alongside the carnivorous plants in the cold and nutrient poor bogs and fens of Manitoba. Manitoba is home to 36 species of orchids but I am going to concentrate on just 4 species that are Carnivorous-Plant companions:
CP39: Grass Pink (Calopogon tuberosus)
CP40: Moccasin Flower (Cypripedium acaule)
CP41: Yellow lady's-slipper (Cypripedium parviflorum)
CP42: Dragon's Mouth orchid -- grows on sphagnum hummocks in bogs and fens. The striking rose-purple colour of the flowers reminds one of the pitcher-plants that grow along side of it. Both are pollinated by bees and although both are scented they offer no nectar reward.
CP43: Grass Pink flower -- grows in coniferous bogs and fens, uses the same hot-pink colour that pitcher-plants and sundews do, and lays a very deceptive trap for its pollinator. The hinged lip on this orchid is uppermost unlike most orchids. It is covered with yellow hairs that are very attractive to bees. When the beef lands on the lip it suddenly bends down throwing the bee on its back onto the sticky column where it deposits the pollen, thus pollinating the orchid. The confused bee flies away to the next flower without getting anything much except a very rough ride.
CP44: Calopogon Sprung trap
CP45a: Moccasin Flower plant -- is a lurid purplish-pink and is covered with hairs. Newly hatched Queen bumblebees are attracted by the colour and scent and force their way in through the slit in the lip.
CP45b: Moccasin Flower lip opening with insect -- They cant get out the same way because of the infolded edges of the slit so they climb up and squeeze out at the top coming in contact with the pollinia. The whole thing is a complete waste of time as far as they are concerned because the flower contains no nectar. Only a very few are dumb enough to try it a second time and this results in pollination problems for the Moccasin Flower.
CP46: Yellow lady-slipper plant -- can grow in coniferous bogs and the flowers are a beautiful buttery yellow much like the leaves of the butterwort. This colour is very attractive to bees and flies, which are the pollinators. Some varieties are beautifully scented as well. The bee enters through the large opening in the lip, looks around and finding no reward has to squeeze out the top coming in contact with the pollinia as it does.
CP47: Yellow lady-slipper with bee -- The bee is having a little rest at the top of the flower in this nice photo.
CP48: In the Carolinas one can see the brilliant Yellow-fringed Orchid (Platanthera ciliaris) growing in the Long leaf Pine savannas. The feathery flowers are such a brilliant yellow-orange that they shine in the sun like a light and can be seen from far away. Their colour reminds one of their Yellow Trumpet Pitcher-plant neighbours and is very attractive to their Lepidopteron pollinators.
CP49: Cypress Swamp where one finds the strange Crane Fly Orchid.
CP50: Crane Fly Orchid (Tipularia discolor) with its many delicate green flowers. The petals and sepals are arranged in a lopsided way giving the flower the appearance of a crane fly. Many insects must be bitterly disappointed when their potential mates turn out to be a fake.
CP51: Perhaps the most striking of all orchid flower mimics are the Ophrys family members that grow in Europe. This specimen from Turkey has flowers whose lips look like the abdomen of a female bee. The male bee's energetic efforts to mate with it scatters the pollen everywhere. The orchid gets pollinated and the frustrated bee gets nothing.
CP52: Fen Habitat where you can see Carnivorous Plants and Orchids growing together in Manitoba.
CP53: Bog Habitat where you can see Carnivorous Plants and Orchids growing together in Manitoba.
CP54: Bog Habitat where you can see Carnivorous Plants and Orchids growing together in Manitoba.
CP55: Yellow Lady's-Slipper -- So there you have it. Carnivorous Plants and Orchids, our beautiful seducers, living in rough conditions and working in similar ways to seduce insects for food and pollination. They need our protection so be careful when walking through bogs and fens so you don't step on them. NOCI runs a couple of field trips each year to the Brokenhead Wetlands in June when you can see these plants. You are very welcome to join us. Please don't try to transplant them from the wild into your greenhouse or garden. Carniverous plants and orchids that have been grown from seed are available from reputable suppliers. If you want to enjoy these plants anytime of the year visit the Assiniboine Conservatory.

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