Hydnora: Fact or Fiction?

Welcome back to the big top for an extraordinary act by the great Laiback gardener plant circus. If you missed the last show with our star bladderwort, they’re on extra in the tent next door. Follow the link and you’ll be sure to find them there.

Let yourself be carried away by the melody and discover before your astonished eyes a parasite sporting the world’s most repulsive flower…

… I’ve named an entire genus: Hydnora!

And once again, artificial intelligence has no talent for spelling or botany! Will it be able to produce a poster worthy of our stars by the end of October? The mystery is complete… Here’s a real Hydnora.

An Invisible Giant

I hope I won’t offend your sensibilities, dear public, by introducing our fantastic specimen of the day. No, it’s not a Pokémon, and no aliens have yet invaded our circus. It is a plant, and a curiosity from the tip of its roots to the tip of its petals.

Let’s start at the beginning, because no flower blooms without a good supply of nutrients. Hydnora’s roots form large rhizomes, rather like a ginger… A ginger a few meters long that looks disturbingly like a spinal column! Sometimes, the soil cracks under the pressure of the rhizomes hiding in it, and it even seems, according to a popular story whose source remains unknown, that this pressure could inflict damage on buildings!

Far be it from me to start rumours, believe me! But the reality is that no scientist really knows the maximum size of this giant root. Who am I to minimize the capabilities of such a mysterious plant? I would never dare say that anything is impossible in the wonderful world of plants! Would it be possible for an individual Hydnora to move the foundations of a house? I wouldn’t even be surprised!

Underground, No Green Needed

From the roots to the flower, that’s what I promised you at the beginning of our number… But it’s impossible to trace anything back since this plant has no stems or leaves.

So let me stay underground a little longer to tell you about the Hydnora’s favorite meal, which is none other than… the sap of other plants.

I hear your alarm, but fear not! Only a few plants need be wary, and you, dear viewers, are not one of them…

Very few plants can survive without green parts. For a plant, no green often means no photosynthesis. But a few species are exceptions to the rule, such as the uniflorous monotrope, a local white plant, or the various species of Hydnora, whose rhizomes are equipped with haustoriums. This is a specialized organ that penetrates the roots of other plants to steal the nutrients that circulate there.

This vampire that sucks the “blood” of other plants is, however, a finicky eater. Each species specializes in a particular host. For example, the Hydnora genus comprises around ten species, all in Africa, which parasitize either euphorbia (in the case of southern species) or acacia (in the case of eastern species). One eastern species is an exception, specializing in trees of the Commiphora genus.

Flowering Horror

Once its energy reserves have been replenished, which can take several years, the Hydnora can produce flowers during the rainy season. These emerge from the earth and look like mushrooms. They have no stems and no flamboyant color, and often go unnoticed with their small size of less than 10 centimetres. That is, until the flower opens!

Special thanks to Sebastian Hatt, the researcher behind this drawing, for allowing me to show you the extent of flower diversity.

Depending on the species, the inside of the flower is pale or bright red or orange and smells horrible. In fact, it’s lucky for you that our specimens are protected behind a screen, because chances are you wouldn’t sit so close.

Depending on the extent of its rhizomes, a Hydnora can produce several flowers. One Somali specimen is said to have produced more than 30 flowers, and the foul smell made it almost impossible to stay in the vicinity.

But why, you may ask?

Honored guests, the answer is both simple and horrifying… The foul smell attracts hydnora pollinators. Nothing original, do you think? Wait for it…

To reproduce, this plant attracts its pollinators with a strong smell of excrement, but who will answer this call? Not a pretty butterfly, I’m afraid! The main vectors of this plant’s reproduction are beetles. Again, not the pretty ladybugs… more like beetles interested in corpses or excrement.

Have you heard of the dung beetle? This insect makes a ball of faecal matter in which it lays its eggs: it’s easy to understand why this smell is so attractive to it!

But this gentle father-to-be may be disappointed when he discovers the subterfuge, and that’s why the plant has to redouble its ingenuity! Once the insect is in the center of the flower, the flower closes in on it for a while.

Don’t worry, she won’t kill the brave insect: it’s not a carnivore, after all, it already feeds by parasitism! But the flower will remain closed long enough – up to a few days, in fact – to ensure that the insect has had a good walk and is covered with pollen when it leaves.

A Mystery of Life

The world of living things is complex. Hydnora is just one example. Tell me, have I aroused curiosity? Or disgust? Even in the scientific community, this plant is mysterious and little studied. In fact, you may have noticed that it has no common name in either French or English. This is usually a good indication that we know very little about the species in question, that we don’t yet fully understand all its mechanisms, evolutionary pathways and virtues.

Why become a parasite?

How to develop a trap-type pollination mechanism?

Who decided to eat this plant in the first place?

Yes, the roots are used in traditional medicine to treat a variety of ailments, including diarrhea, ironically enough. Acne creams are also made from this plant in Africa. The fruits, which take two years to mature underground, are edible. So don’t judge a book by its cover, or a plant by its smell.

Some go so far as to say that the Hydnora is the world’s weirdest plant. What do you think, dear audience? Your stage manager doubts it. Not that I know of a single plant worthy of the title – who am I to make such a claim? But in the wide world, as in this plant circus, every curiosity has its place and is welcome.

Come back next Thursday for the next issue, the next specimen, the next adorable monstrosity that will introduce you to the strangeness of the magnificent world of plants!