A team of researchers from the University of Haifa have stumbled upon a rare desert plant living in Israel’s mountainous Negev desert, which can irrigate itself.
The plant, the desert rhubarb, Rheum palaestinum, was first classified by a local Israeli botanist about 70 years ago. It has adapted to harsh desert climates by developing specially designed leaves — broad and with grooves and channels — to funnel even the slightest bit of rainwater directly to its roots.
It is the only known plant of its kind in the world, and could teach science — and people — new ways for maximizing water distribution in agriculture, especially in extremely arid regions. Locals say it is found only in Israel and nearby Jordan.
ISRAEL21c asked one of the Israeli researchers, Prof. Simcha Lev-Yadun, a botanist, who recently measured the water intake capabilities of the desert rhubarb, if it could lead to new water-collecting devices (like the ones we’ve written about here — see the story on Tal-Ya Water) based on bio-mimicry.
“You are 2,000 years too late,” he says. “This same type of typography that we see on the plant’s 1/3 square meter surface was done on the scale of hundreds of meters, if not kilometres, by ancient people who lived in the Negev Desert until the first millennium CE. I am sure that people found this simple physical rule and exploited it,” he adds.
No leaves unturned
Aside from being a botanist, Lev-Yadun is also an archeologist, with a first and second degree in the field. He explains that Nabatean people living in the Negev Desert after the second Temple Period and the late Byzantine period, would pile stones in mounds that the local Arabs call “mounds for grapes”.
These stones were set up to funnel water down a hill for irrigation purposes, before the water “infiltrated the hill,” says Lev-Yadun, and resembled the surface of the rhubarb.
With his research partners Gadi Katzir and Gidi Ne’eman, also from the University of Haifa, Lev-Yadun ascertained that the reason the rare rhubarb flourishes in hostile areas in the desert, is because it can collect up to 16 times more water than other plants growing in the same region.
They findings were published recently in the journal Naturwissenschaften.
Characterized by large rosette leaves with deep grooves, Lev-Yadun — also an avid hobby photographer — says that the leaves when photographed up close starkly resemble the mountainous regions in which they grow.
Like rainwater through a valley
And the water on the leaves of the rhubarb travel off its surface, in much the same way that rainwater flows through the valleys and slopes of the mountains in the Negev Desert, but on a very different scale.
According to the recent study, the desert rhubarb can harvest 4.2 liters of water each year, with the largest of its kind collecting an astounding 43.8 liters. Compared to an average rainfall of 75 mm a year, the rhubarb has found a way to make the most of its limited environment.
Additional research into the mechanics of the plant finds that the plant not only funnels the water to its roots, but the water is able to penetrate 10 cm into the soil, 10 times deeper than if the rain landed by itself on the desert sand.
A tough waxy surface on the leaves, lends additional support in funneling the water to the roots where it is needed.
Can scientists take home a message from this plant and create the ultimate irrigation machine? Lev-Yadun has no designs on such an invention, but doesn’t rule out the possibility.
“It’s a rare plant. We can’t plant them by the billions and irrigate with them.” But, he adds: “theoretically one could do the same with plastic and collect the water. This is already done on a small scale here and there,” adds Lev-Yadun.