I was going to write this in my own words, but the article is very entertaining, and I don't believe I could do it any justice, so here you are:
[FONT=Arial, Helvetica, sans-serif]Forget soil and fertilisers, there is one plant that needs only the air that we breathe. Darren Crayn explores the salt marshes of Venezuela in search of an incredible plant which has captivated him for over 20 years.
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[FONT=Arial, Helvetica, sans-serif][SIZE=-1]Tillandsia like to live perched up high on cactus.[/SIZE][/FONT]
[FONT=Arial, Helvetica, sans-serif]It was a perilously hot morning. I could just make out the ghostly visages of cactus plants, tall and elegant, through the shimmering heat waves rising from the dusty plain. I knew that out here in the seasonal salt marshes of the Venezuelan carribean coast there grew a plant that had a much harder life than these tall cacti. A plant that never knew the luxury of a quick drink from the sodden soil after a rainstorm. It was out here somewhere, all I had to do was find it. And I knew where to look, because in this parched landscape the little plant lives perched on top of the cacti![/FONT]
[FONT=Arial, Helvetica, sans-serif]I had come to these salt marshes on a personal pilgrimage, to meet face to face with the tillandsias that had so entranced me in my youth. [/FONT]
[FONT=Arial, Helvetica, sans-serif]As I trudged across the cracked and bone-dry landscape, I remembered the day twenty years before when I saw my first tillandsia. It was just a hairy little tuft of a thing, stuck to a rock in a local plant nursery on the north coast of New South Wales. It was living, there was no doubt about that, but there was no soil and no obvious roots. Instead, it was sitting, anemone-like, in a big blob of rubbery glue, with its stiff, grey-green tentacles twitching gently in the breeze. It looked other-worldy, like no plant I had seen before. I was intrigued.[/FONT]
[FONT=Arial, Helvetica, sans-serif]Where to get a drink?[/FONT]
[FONT=Arial, Helvetica, sans-serif]My companion across the salt marshes that morning was the well-known Venezuelan plant physiologist, Dr. Ernesto Medina. It was the dry season and the sustaining waters had long retreated from the marshes leaving a dry, dusty, and salty soil. But around me, groups of hardy plants appeared to be managing quite well, even under such adverse conditions. These plants have found ways to overcome the one over-riding problem with living in such arid habitats, and that is, where to get a drink. [/FONT]
[FONT=Arial, Helvetica, sans-serif][SIZE=-1]Plants in the tillandsia family include this Bromeliad[/SIZE][/FONT]
[FONT=Arial, Helvetica, sans-serif]The cacti have adopted one common approach to this problem. They drink heartily from the soil when water is available, and store in their fleshy stems what they dont immediately use, to get them through the dry periods. But the tillandsias, living high up on the cactus thick, fleshy arms, dont get the opportunity to drink from the soil. Their roots are highly modified and are good only to anchor them, limpet-like, to their spiny hosts. They are not parasites: the roots dont penetrate the cactus thick skin, so the reservoirs of vital water within are off-limits. There they sit, high up in the dry, wilting air. You could hardly think of a less hospitable place. But tillandsias manage to thrive, so where do they go for a drink?[/FONT]
[FONT=Arial, Helvetica, sans-serif]Ernesto led me toward a large and impressive-looking
Pilocereus, the dominant cactus in these coastal Venezuelan plains. At its base, sun-bleached flotsam littered the cracked soil as a testimony to this arid lands other life as a saltmarsh. The upper reaches of the cactus spiny limbs were festooned with freeloaders, their tentacle-like leaves combing the breeze like warped green anemones. These were the tillandsias,
Tillandsia flexuosa to be precise. Suprisingly, they are close relatives of the pineapple. Standing there before what looked like a frayed and twisted rope of fat snakes, I couldnt help but think maybe they were closer to Medusa. [/FONT]
[FONT=Arial, Helvetica, sans-serif]Up close & personal[/FONT]
[FONT=Arial, Helvetica, sans-serif]I had to get a closer look. Turning one of the leaves in my fingers I marvelled at the fine, light grey fur covering its surface. While it gives the leaves a gorgeous silvery lustre, this fur is there for more than that just aesthetics. In addition to the protection it gives to the plants tiny green photosynthesis factories (chloroplasts) against excessive sunlight, there is an even more remarkable function. [/FONT]
[FONT=Arial, Helvetica, sans-serif]Looking carefully through my magnifying glass, I could see that this fur is not made up of simple hairs, but it is a veritable forest of tiny, fragile cups whose rims fan out into narrow, tongue-like bits (lets call them wings) on one side. I knew that these beautiful structures must be important:- why would a plant living in such a harsh environment invest so much energy to produce them if they were useless?[/FONT]
[FONT=Arial, Helvetica, sans-serif][SIZE=-1]Trichomes, the ' little cups' which make living on air possible.[/SIZE][/FONT]
[FONT=Arial, Helvetica, sans-serif]I knew that these little cups, or trichomes (pronounced try-combs), allow tillandsias to do something quite amazing and unparalleled in the plant world. Rather than absorb water through their roots like other plants, tillandsias use their trichomes to drink through their leaves. This astounding feat led the great botanist Carl Mez to coin for tillandsias the name atmospherics, but to gardeners and hobbyists they are simply air plants.[/FONT]
[FONT=Arial, Helvetica, sans-serif]While botanists have known of the existence of these curious trichomes since the pioneering work of Dr. Mez over a century ago, only recently has their role in water uptake been fully revealed. We now know that each trichome is made up of a lot of little cells, some of which are living, and some of which are dead and are just an empty shell. When a drop of rainwater falls on the surface of the leaf, it spreads very quickly into a thin film due to 'capillary action. This is a peculiar vice of many liquids that, when faced with a very narrow space (like the space in the centre of a thin needle) they want to defy gravity, and squeeze themselves up into it. [/FONT]
[FONT=Arial, Helvetica, sans-serif]On the tillandsia leaf, it's the gaps between the trichomes that constitute the 'narrow spaces' which result in the capillary action. When the water comes in contact with one of the dead cells in the wing of a trichome, it is drawn into it like into a sponge, swelling the cell to several times its original size. Then osmosis takes over, and the hapless water molecules are dragged by this irresistible force out of the dead cells into the living cells in the centre of the trichome. Once in the living cell, the water is caught and the plant may use it how it likes. The whole process from rain to gain is simple but effective, and it all happens, literally, in the blink of an eye. [/FONT]
Now, if a trichome can be produced to harness rainwater, could one not (at least in the terms of cannabis) be evolved to harness light?