The Secret Sex Lives of Plants

The Plant That Explodes

Some cucumbers go to great lengths to disperse their seed. Ecballium elaterium, a Mediterranean member of the gourd family, is called the squirting or exploding cucumber for good reason.¹

While ordinary cucumbers rely on the likes of humans and other animals to spread their seed, this excitable specimen has a rather less subtle means of propagating itself. It explodes, shooting a jet of its seeds up to six metres (20 feet) away in a process called ballochory,² or ballistic seed dispersal.

To achieve this, the vertically-hanging fruit is put under tremendous internal strain as it ripens. It becomes filled to bursting with seeds and a viscous sap, reaching the pressure of 27 atmospheres³- roughly the same as you’d experience nearly 280 metres (915 feet) underwater. When the pressure becomes too great, the fruit drops off and the sap is ejected out in an arc, carrying the seeds away in its infamous ‘squirt’.

The Orchid That Lies

Orchids are one of the biggest and most diverse families of flowering plant: there’s 25,000 species of them, found across all habitats of six continents. The reason they’ve become so successful at spreading themselves far and wide is a simple one. They’re extremely good at reproducing in bizarre and devilishly clever ways.

One such species, the Ophrys, or bee orchid, is found in remote Mediterranean mountains. As its name hints at, it seduces male bees by impersonating the female as viewed from behind. It even gives off a similar scent.

The poor insect, duped by this act of sexual deception, lands on it to do the deed – literally buzzing with excitement. In its confusion and frustration, it picks up enough pollen to take to the next orchid that tricks it. Clearly you can fool a bee more than once.⁴

The Tree That Changes Gender

Brunch favourite the avocado is quite unlike any other plant. In its natural environment of South Central Mexico, avocado trees can switch genders in a matter of hours. Their flowers contain both male and female sex organs, with neither functioning at the same time. Instead, it has female and male ‘stages’, which reduces the likelihood of self-pollination.⁵

So, if the flower is female when it opens, then its stigma is ready to be pollinated by insects. But when it reopens the next day, a remarkable transformation will have take place: its stigma is no longer active, replaced instead by its male sex organs, or stamens. It now uses this to spread its own pollen, before the flower closes once more – this time for good.⁶

The Slumbering Pollinator

The popular fruit of the hazel tree comes into, well, fruition in a rather peculiar way. Like the avocado, these trees carry both male and female parts. Its male parts are catkins – long, droopy flowers that burst forth rather suggestively in the depths of winter. These, as you may well guess, are its pollinators, and they spread their seed on windy days. Nearby trees pick them up with their small, red ‘female’ flowers. The hazel tree can’t self-pollinate, but since its pollen can travel up to 50 feet, that’s never a problem.

Unusually, nothing happens the instant that pollen reaches the flower. Instead, the pollen lies dormant until late spring, when it then finally fertilises the tree. And after another six weeks, the nuts are fully grown at last.⁷

The Sexual Predator

If the bees hanging around the Ophrys thought they had it bad, they should meet the unassuming Jack-in-the-pulpit, or Arisaema triphyllum. Or rather, they really shouldn’t. This deadly woodland perennial, found in eastern parts of North America, has an interesting reproductive method. The top flap of its white and brown-striped flower is darker inside.The bees fly in – where the darkness disorientates them – and they pick up pollen as they’re bumbling about. Once loaded up with it, they spot what appears to be an escape route...

But it turns out they’ve been fooled! This is the female base of the flower and there’s no way out. The poor bee, after inadvertently pollinating the plant’s pistil, is left to die, having served its purpose.⁸

The Plant Pickup Joint

In French Guiana, South America, you will find the Philodendron solimoesense – a flower that acts as the insect equivalent of a nightclub. The lily-like flowers, complete with a suggestively fleshly white stalk and ‘copulation’ chamber, produce heat, heady perfume, ample food, and a dark, quiet place to sleep it all off.

This is the perfect place for the scarab beetles to meet and mate – and perfect for the Philodendron, too. The bugs pick up its pollen during their nocturnal adventures and then spread it to other flowers, thus promoting the Philodendron’s own sexual success.⁹

The Stinky Colossus

Not all flowers are pretty, nor even nice-smelling. Such an example is another deceitful character, the massive Amorphophallus titanum (titan arum). It’s also known as the ‘corpse flower’ because of the rancid, malodorous fumes it produces to attract carrion-loving beetles and flesh flies. As they sniff out what they believe to be a tasty meal of rotting flesh, the scavenging bugs investigate the flowers, inadvertently transferring pollen from one stinking specimen to the next.¹⁰

They’re truly magnificent to look at, with red and brown petals and an often terrifyingly large inflorescence. These can grow to over three metres (10 feet) in height and resemble a giant green finger or baguette, proudly pointing skywards.¹¹

It seems the sex antics of plants are way more varied than anything we could think of in even our wildest dreams – or nightmares. These peculiar propagators bring a whole new meaning to the term ‘a bit fruity’.

This article was commissioned as part of 'Our Green Planet'. This is a digital initiative, from BBC Earth in association with The Moondance Foundation, to raise awareness for the beauty and fragility of our planet’s green ecosystems. Discover more here. #OurGreenPlanet.

Featured image © Guenter-Fischer | Getty Images

1. Squirting Cucumber, 2. Ballochory Seed Dispersal, 3. Cucumbers Feel the Pressure, 4 Bee Orchid, 5. Avocado Trees, 6. Avocado Pollination, 7. Hazel Tree, 8. Jack-in-the-pulpit, 9. Philodendron solimoesense: the Plant Pickup Joint, 10. Corpse Flower, 11. An Enormous Inflorescence