At first appearance, it is one of nature’s more shambolic efforts, no more than a scruffy, hunched heap of vegetable matter.
- It’s older than the Roman Empire, taller than the Statue of Liberty and as heavy as 7 blue whales
- It weighs up to a whopping 30kg, has a diameter of 50cm and is the biggest seed on the planet
Several esteemed 19th-century biologists, including Joseph Hooker (then director of Kew), called it the world’s ugliest plant, while FW Oliver (professor of botany at University College London) decried it as the “ugliest plant in creation”. But they both noted its hidden depths.
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What does Welwitschia mirabilis mean?
Welwitschia mirabilis was named by Joseph Hooker. The genus honours its discoverer, Dr Friedrich Welwitsch (then director of the Lisbon Botanical Garden), while mirabilis means remarkable, marvellous or wonderful. This characterful plant is all of these.
Where does Welwitschia mirabilis grow?
Growing only in the Namib Desert – a strip of desert that runs from Angola into Namibia, and one of the oldest in the world – this ‘living fossil’ (unchanged for more than 200 million years) has had plenty of time to adapt to one of the harshest environments on the planet.
What does it look like?
But don’t be fooled by its shabby appearance, which belies its true nature. Welwitschia mirabilis is also referred to as tree tumbo and (my favourite) tweeblaarkanniedood – a very descriptive Afrikaans word that sums up this botanical oddity, translating as ‘two leaves; can’t die’. Indeed, it is a true survivor.
Like a large woody carrot, it has a long taproot that can penetrate ancient desert soils to depths of more than 30m. Only the top 30cm or so is above the surface, mostly hidden by a tangle of leaves, of which it has only two.
How big is Welwitschia mirabilis?
The tough, waxy leaves are broad – up to 90cm across at their bases – where they are continuously extruded from either side of a two-lobed crown. Depending on local conditions – as well as the effects of gritty winds and the predation of many species, including the black rhino – these leaves reach variable lengths before splitting and fraying.
Sometimes they stretch more than 6m into the desert, like the tentacles of a sea creature; sometimes they become tangled, resembling a nest of noodles.
How old are the plants?
Some Welwitschia plants are estimated to be 1,500-2,000 years old.
How has Welwitschia adapted to the desert?
To survive the harshness of its desert home, Welwitschia has many tricks up its leaves. Moisture is not very evident in the desert, yet it can be found if you know where to look, and the plant is a master at this.
Welwitschia plants are often found growing in clusters or in linear troops. Their prostrate piles map subterranean watercourses, whose hidden pools and rivers they reach with their deep taproot.
But just as important is their ability to drink the fog, which they do in several ways. When condensation forms on leaves near the base, the dew is channelled towards the plant’s centre.
These leaves are also covered on both surfaces with thousands of microscopic pores, called stomata, which in most plants open on the underside of the leaf. Welwitschia uses these pores to ‘breathe in’ saturated air overnight, then closes them as soon as the day starts to heat up.
Its thick, waxy leaves, and the fact that it utilises CAM photosynthesis (meaning it doesn’t need to open its stomata during daylight hours – the only gymnosperm not to do so), allow the plant to hang on to its gains.
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In addition, just below the sandy soil surface, a lattice of finer roots spreads out in all directions to collect the moisture that condenses from the fog banks formed by the meeting of the cool air from the Benguela Current and the red-hot desert.
This fog only penetrates the continent by around 100-150km. It is no coincidence that beyond this zone, no Welwitschia are growing.
How is it pollinated?
Each plant is either male or female, producing cones that are pollinated by insects. The resulting bare seeds, however, require several days of rain to germinate, a rare event in the desert. Welwitschia, then, must grind on doing what it does for hundreds of years to stand any realistic chance of procreating.
Does anything live on Welwitschia?
Each Welwitschia is an island in a desolate sea, bustling with reptiles or small mammals utilising its shade, and a plethora of bees, wasps and flies jostling for nectar. There is nearly always a herd of a black-spotted bug, Probergrothius angolensis, often called the Welwitschia bug as it is found nowhere else. It presumably feeds on the plant’s sap.
