Orchids don’t always reward their pollinators – sometimes they mislead them. From flowers that mimic insect mates to flowers that smell like rotting fish, orchids have evolved remarkable strategies to ensure their reproductive success. Experts at the US Botanic Garden in Washington, DC, explain how these botanical tricksters work and why, despite their impressive bag of tricks, many orchid species are currently considered endangered.
Mandana Tadayon: Orchids are among the largest plant families on earth – often swapping the top spot with daisies when new species are discovered.
George Guenther, Advanced Gardener, US Botanic Garden: Orchids are incredibly diverse. There are many thousands of species around the world. They have evolved into many different shapes and growth habits and flowers and things like that, to facilitate pollination and to adapt to their environments.
Tadayon: Dubbed ‘masters of deception’ by the experts at the US Botanic Garden in Washington, DC, the orchids you’re about to see each have a unique trick to lure in pollinators.
#1 Lepanthes, Pollination mechanism: Sexual deception
Guenther: So this case contains orchids pollinated through sexual deception.
Specifically, the plants we have on display right now are species of Lepanthes.
Some species of Lepanthes have been observed to be pollinated through pseudocopulation, meaning that in many cases a male mosquito – small mosquito – visits the flower thinking it is a mate.
And in doing so, pollen transfers when it interacts directly with the flower’s reproductive structures.
#2 Phragmipedium PearceiPollination mechanism: False trap deception
Guenther: Contrary to popular belief, the sacs on the flowers are not actually traps to consume or trap insects permanently, but they actually function as part of their pollination mechanism.
They are often pollinated by insects that visit the flowers, fall into the bags like a trap and are unable to fly back out of the bags. So what they have to do is crawl out the back of the flower.
And in doing so, they deposit pollen and then pick up the pollen from this flower as they leave it. The spots specifically on these flowers are meant to imitate aphids. There are small flies whose larvae naturally feed on aphids, and so the flies visit the flowers to lay their eggs among the aphids, then are tricked into the traps and then have to pollinate the flower on their way out.
#3 Bulbophyllum Picturatum, Pollination mechanism: Fragrant deception of rotten meat
Guenther: Bulbophyllums have very interesting pollination mechanisms. Many of them use very strong smells to attract things like flies to visit their flowers. They can smell like excrement, rotten meat, rotten fish, things like that that are really good at attracting flies.
And when the flies land on the flowers, they have a little hinged flapping lip, and that lip kind of trips and turns the fly into the center of the flower, the column, where the reproductive structures are, and the pollen is thus transferred to the fly from Bulbophyllum. So like this Bulbophyllum in this case, here has a rather strong fishy smell. It’s actually even more noticeable on warm, sunny days when you consider that the flies are active.
#4 Coelogyne CristataPollination mechanism: Food deception
Guenther: Members of the group of Coelogyne are sometimes pollinated through food deception. So they have a scent, and it attracts bees and wasps and things that come in to collect nectar. And sometimes the plants have some nectar, but they don’t really give any reward.
They just trick the insect into coming.
#5 Spathoglottis KimballianaPollination mechanism: Color and scent deception
Guenther: This Spathoglottis actually use bright yellow colors and sweet scents to attract pollinators such as bees who will then emerge hoping for nectar and not actually end up receiving nectar but incidentally pollinating the flowers in the process.
And the color is a big part of it. These bright colors, this bright yellow, are part of the attraction. You’ll often see bright colors like reds, yellows, pinks and things like that that help with some of that attraction.
#6 Angraecum ComorensePollination mechanism: Nocturnal scent deception
Guenther: These orchids are actually a group of orchids that offer a reward to their pollinators. They are night scented. They usually smell sweet, sometimes like a rose scent. And the reason they smell like that is actually to attract moths that will visit them at night.
The moths use their long proboscis to drink nectar from these long nectar spurs on the back of the flower. So you can imagine a moth has a little tongue that will roll all the way to the bottom there.
It is a known related species, Angraecum sesquipedalewhich is known as Darwin’s orchid. Charles Darwin knew that species of orchids.
It has a 12-inch-long nectar, and Darwin assumed it was a moth with a tongue and proboscis long enough to get to the base of that nectar for its reward. But in his lifetime they never discovered the mill. It wasn’t until decades after he died that they actually discovered a large hawkmoth that visits the flowers at night in Madagascar and pollinates them, confirming his theory.
Tadayon: Despite the variety of orchid flowers around the world, many species are considered endangered.
Devin Dotson, Senior Communications Specialist, US Botanic Garden: Much of it is man-made. You over-harvest or over-harvest, but a lot of that is loss of habitat, right? As things develop, perhaps it is changed to agriculture, or it is made to other human uses for housing or other purposes. Habitat is lost. But the other one is going to be climate change, right?
I mean, as things change, especially with heat and drought and flooding, those three things have a very big effect on plants. So for things like orchids, if it’s in an area that normally wouldn’t have had standing water, it wouldn’t have been flooded or flooded or anything. And if it happens repeatedly, suddenly, the orchid may not survive, because it is under water a lot.
Or if the temperatures change, right, where the summers are suddenly even hotter than they’ve been before, the orchid potentially can’t survive in that location anymore. Pests and diseases are also affected by changing weather, because if you don’t have really hard freezes in some places, the pests and diseases may not die. And so pests and diseases can continue to last all the way through winter to spring. You have larger populations or they can spread even further because they don’t get knocked out by the really cold freezes in the winter.
Tadayon: So if you travel and see beautiful orchids in the wild, experts say the best thing to do is leave them where they are. Taking orchids from their natural habitats – or trying to move them across borders – is illegal and puts already vulnerable species at risk. When orchids are confiscated from the illegal trade, some end up in the US Botanic Garden, which has served as a plant rescue center for decades. There, impounded orchids are cared for, restored to health and given a second chance to bloom – helping to protect these remarkable plants for the future.
