Sunday, July 12, 2009
Having not thought about rhubarb for eons before finding some in a supermarket here a few weeks ago, I was surprised to see that today a related plant – “Desert Rhubarb” – is making the local news.
“Desert Rhubarb” -- Rumex hymenosepalus – pictured above, grows only here in the Negev. It's just been discovered that it's a water-harvesting plant.
Get that? It actually collects water and funnels it to its own roots. The plant has created its own natural irrigation system.
Researchers at the University of Haifa began studying the plant when they saw it wasn’t constructed like most desert plants. Most leafy plants that thrive here have tiny leaves, in order to reduce transpiration of precious moisture.
But not Desert Rhubarb – it has enormous waxy leaves that measure over two feet across, each one with a network of grooves. Each leaf grows on a ridged stem, so the way it works is that the leaves collect whatever rainwater – or dew – falls, then channels it via the ridges in the leaves and stems to the plant’s base to irrigate it. The researchers said that its natural irrigation system allow it to collect 16 times more water than it would get if it relied on surface water.
"When the annual rainfall is three inches, they see something like 17 inches of rainfall," said Simcha Lev-Yadun, one of the researchers. “Compared to the one inch of rain captured by other nearby desert plants, desert rhubarb captures between 16 and 17 times more water. This ‘leaf-made mini oasis’ creates a Mediterranean climate for the plant in the middle of the desert.”
Desert Rhubarb is different in another way, too. Instead of having very shallow roots, to quickly take up any rainfall on the surface, the Desert Rhubarb has very deep roots. Since it has its own irrigation system, it doesn’t need the shallow roots.
But here’s the question I’m sure you’re all wondering about: can you eat it?
The answer is yes – it sounds as though it’s much like regular rhubarb: Young leaves can be cooked in several changes of water to remove the bitter tannin. The stems are “crisp and tart” – no kidding –and are used in pies, cooked with sugar or baked. You can even eat the flowers, boiling them to make a drink.
“Children eat it raw in the early spring,” it says at the ‘Plants for the Future’ database. http://www.pfaf.org/database/plants.php?Rumex+hymenosepalus
Which children might be a logical question…. Only those who would eat crabapples, I presume. And no child will willingly eat a crabapple, either, unless it’s recently been liberated from a neighbor’s tree. Goodness knows there’s no other reason to eat the bitter little things.
Water -- and the conservation thereof – is on a lot of people’s minds in Israel. Draconian new water usage rates were originally scheduled to take effect starting today, but have been postponed for a week. Use more than your allotted share, and you’ll be charged one shekel for every liter over – a liter is about two pints, for you US readers. A shekel is worth about 25 cents. That could get real expensive really fast.
I’ve always used the bucket-in-the-shower routine to water plants, but several months ago I set up a Gunga Din Water Toting System (me) to collect wash and rinse water from the washing machine and ferry it to the roots of my precious trees. I wouldn’t put in on potted plants, but the in-ground trees seem to be thriving on it.
Now that I think of it, it might be simpler to just hire some Desert Rhubarb plants to harvest some water for me. Now that's an idea.