Nine Ways to Lure a Lover, Orchid-Style

Orchids of the genus Psychopsis are often called “butterfly orchids” because of their resemblance to the dazzling insect. “The three sepals [modified leaves] look like antennae sticking out of the top, whereas the three petals are more wing-like,” says horticulturist Tom Mirenda, of Psychopsis versteegiana (above). Even the column—the reproductive structure in the center of the flower where the male and female parts are fused together—looks like part of an insect, the head.

When a plant looks like an insect, one of two scenarios is probably at play, explains the Smithsonian’s orchid specialist. The flower might be mimicking a female insect so that an inexperienced male of the same species comes to the flower looking to mate. This ploy is called pseudocopulation. Or it might appear to be a particular insect in order to lure that insect’s predator or parasite. Either way, the duped insect is there to aid in pollination.

American botanist Calaway Dodson claims to have seen zebra butterflies, in the 1950s, attacking this Central and South American orchid species, as if to defend their territory. It is possible that pollen was transferred in this altercation. But no one has actually witnessed the pollination of this type of orchid in the wild. “It is a species that has been in cultivation for well over a century, and yet no one is really sure what pollinates it or why,” says Mirenda. “It is just amazing that such a mystery has lasted all this time.”

Also known as Venus’s slipper orchid, Paphiopedilum venustum, found in Southeast Asia, uses its bold coloration to bait insects. Often, when insects land at the center of the flower, they fall into its cupped lip. In orchid terminology, the lip is one of the flower’s three petals and serves as a landing pad of sorts for its pollinators. “Inside, in tight quarters, insects have difficulty spreading their wings and flying out again and have to climb up the textured rear of the pouch,” says Mirenda. They escape—but in the process, the insects pick up pollen, which they ultimately bring to other flowers

Hot environments are not exactly conducive to pollinator activity. So African orchids called Aerangis distincta make the most of the cooler night hours. Beginning at dusk, the white orchids, made ever more radiant by the moonlight, emit a powerful fragrance that attracts moths. When a moth lands on or hovers above the orchid’s lip, it sticks its tubular mouthpart, called a proboscis, into the lip and down a long nectar spur that dangles from the blossom.

Only hawk moths with a proboscis of just the right length and curvature can suck up nectar from the bottom of the foot-long drinking tube. This specificity prevents cross-pollination between different orchid species. “Charles Darwin crystallized his theory of evolution after observing a similar orchid, Angraecum sesquipedale,” says Mirenda. “He theorized the existence of a moth with a 12-inch-long tongue, based on the flower’s morphology.”

Male euglossine bees collect fragrances from flowers. “The males with the most complex array of fragrances get all the ladies,” says Mirenda. But when the bees land on male Catasetum orchids, they also get a swift wallop on the head. “The flowers basically mug their pollinator by shooting really large pollinia at them when they touch a little trigger switch in the flower,” says Mirenda.

After being whacked, as a reaction, the bees retreat to shelter—in this case, to the Catasetum’s female flowers (above). The helmet-like flowers, found in Central America, actually resemble the nests that the bees build. There, while feeding on nectar, the bees deposit the pollen.

The bucket orchid, Coryanthes macrocorys, also ensnares euglossine bees. When an unsuspecting male bee visits the orchid, looking to pick up a scent, it falls into the flower’s bucket-like lip. The orchid secretes a sticky liquid, which nearly drowns the bee. “Desperate to escape and unable to fly out due to its wet wings, it must squeeze out an escape hatch in the back of the flower,” says Mirenda. Conveniently, the orchid’s pollen is in that hatch and adheres to the fleeing bee.

The reddish, furry lip of Bulbophyllum echinolabium not only looks like dead meat—Mirenda compares it to a “bloody limb of a mouse”—but it smells like it too. Occasionally, when the Indonesian orchid is in bloom and Mirenda is giving a tour of the Smithsonian’s greenhouse in Suitland, Maryland, he will include it in a lineup of fragrant flowers just to rattle sniffing visitors. “You usually have to get up pretty close,” says Mirenda. “But on really hot summer days, you can smell it from a distance.”

The putrid stench attracts flies, which land on the foot-long orchid, thinking it is a good place to lay eggs. “As the fly moves around on the lip, the lip rocks and puts the fly’s body in contact with the pollenia, which it then takes on its back to some other flower some distance away,” says Mirenda.

Most orchids in the genus Masdevallia release fetid smells to attract fruit flies or fungus gnats. But Masdevallia glandulosa, found in Ecuador and Peru, releases a sweet aroma. Some have compared the smell to that of cloves. It wafts from little beads, or glands, that look, as Mirenda puts it, “like little purple hot air balloons.” He is not sure what pollinator the orchid attracts with its scent. “But it is a very interesting adaptation,” says Mirenda, “And it makes for a really dramatic photograph to see all those fragrance glands.”

Like Aerangis distincta in Africa, Habenaria medusae in Indonesia is a white orchid that is pollinated by moths. “If you look at the flower from the side, you’ll see that there is a nectar spur behind each flower,” says Mirenda.

The lip of the Indonesian species, however, is a dramatic splay of serpentine-like strands. Hence the name: medusae, after Greek mythology’s Medusa, whose hair turns into snakes. “There is something about the compound vision of moths and butterflies that makes fringe extremely attractive to them,” says Mirenda. “I don’t know if it is somehow focused, when you have a hundred little lenses in your eye, into some delightful shape. Until we can get inside the brain of a moth, we don’t really know what it is that they see.”

Though it may look commonplace, this solid red orchid is actually quite rare. The species, Cattleya (Sophronitis) coccinea, requires cool temperatures and lives at elevations of 2,000 to 6,000 feet in the forests of Brazil. “In the upper elevations where it is cool, there is much less insect activity, since insects are coldblooded. So as you get higher and higher up in the mountains, you tend to see these brighter colors attracting warmblooded pollinators,” says Mirenda. The brilliant hue of coccinea, for instance, lures hummingbirds.

Though he is not certain if this is the case for coccinea, Mirenda says that, in general, flowers with a strong visual cue are often just a tease—offering no reward, such as nectar, for the visiting pollinator. “It is all about manipulation,” says Mirenda.