Saturday, 19 September 2015

A Plant's Guide to Desert Survival




Water. That's one thing us plants need on a regular basis or else we'll just shrivel up and die, right? If your owner is going away on holiday they damn well better get the neighbour to water us; or get some of those special hydrating crystals!



But did you know that not all plants are like this? Oh no, some plants can survive for yeeeaars without any water... some plants amputate their own limbs to survive! ... Some plants can even come back... from the dead!

How do they do this?! I hear you ask, is it magic?

Not quite, but it's close! These amazing plants have special adaptations that enable them to live right out in the middle of a desert! The last place you'd ever find me!

You can categorise these fellas into four main types. Let's have a look at them in more detail:





1. Ephemerals

 Let me introduce you to Lily, well, Desert Lily if you want her full name. Appreciate her beauty while you can, as you may not see her again for years. Ephemeral plants like her can lie dormant for long periods of time. She stores energy in her roots, hidden deep underground and protected from the sun. Her leaves and flower above ground shrivel up in the heat, to an outsider she would appear to have died. Only when there is a proper rain shower that soaks right into the soil will she wake up, like sleeping beauty. But she won't be around for long. Ephemerals have very short like cycles, they germinate, flower and disperse their seeds all in just a few weeks before the drought sets in once again.


2. Halophytes

Now these guys really deserve some respect, for they can grow in salt! You remember that time you tried to protect your garden strawberries from slugs by putting a ring of salt around them, and all it did was kill off your strawberry plants altogether? (Well at least the slugs didn't get any either!). Well most plants can't stand to have their roots near any soil, it sucks the water right out of us and we'll dry up and die even with water. But these guys, they have some pretty cool tricks up their sleeves (or should that be leaves?).

Unfortunately all that insolation and exposed soil in deserts means there's lots of evaporation, and this means all the salt in the soil is drawn up by capillary action and concentrated just where we don't want it. But does this pose a problem for Mr. Saltbush? Of course not! For he has special salt glands and if conditions become too saline he just excretes this salt onto his leaves. Not all halophytes work in the same way. Some of them have special roots that make sure no salt is absorbed, even if it's already dissolved in their water supply, while others have special compartments in their tissues, which store excess salt and keep it away from growing cells. All in all, these plants are pretty impressive,



3. Phreatophytes

The Mesquite is a common but remarkable tree that has adapted to arid conditions from its leaves to its roots. The root system of this tree is not only spread far out to the sides, to make the most of any rain that does fall, but its taproot can reach down over 50m to find water, the deepest ever recorded for a tree!












4. Xerophytes 

Probably the most commonly associated plant with an arid climate, the Xerophyte is the Survivorman of the desert, built to withstand the harshest of droughts.

Instead of leaves, the majestic Saguaro Cactus is covered in small spines to protect itself from thirsty animals. For inside this giant plant, which can grow up to 18m tall and live up to 200 years, a whole ton of water can be stored! If you look carefully you'll notice that they have pleats down their stems, allowing the plant to expand as it fills with water. Not only this but they are covered in a thick, waxy cuticle to make sure their water doesn't evaporate (via transpiration) in the hot sun.


The Quiver tree, another succulent (which just means that the plant is thick and fleshy) has found some ingenious ways to reduce water loss. As well as thick, waxy leaves and the ability to store water in its trunk, it is also covered in a fine white powder, that reflects the sunlight and helps to keep it cool. And if things get really bad it has another, incredible solution. Check out the video below to find out!








I hope you found that interesting... or at least useful for your studies! Before I go, here's a couple of reminders of some our desert plants' key features:





Images taken from:
http://www.calflora.net/bloomingplants/desertlily.html
http://www.nrcs.usda.gov/Internet/FSE_MEDIA/nrcs144p2_049815.jpg
http://visualsunlimited.photoshelter.com/image/I0000t31HiiOECUI
https://upload.wikimedia.org/wikipedia/commons/1/19/Saguaro_Cactus_AZ.jpg
http://www.worldwanderingkiwi.com/wp-content/uploads/2012/07/Natasha-053-e1341465261636-1024x941.jpg

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