If you’re this kind of plant, you don’t
want to be living in the deserts of Las Vegas,
which can easily reach over 100 degrees Fahrenheit,
or 38 degrees Celsius, in temperature and
receive only around 11 centimeters of rainfall
yearly.
So what do the mighty desert plants do differently
to be able to live in such environments?
--It’s not easy.
There’s a reason why forests are not seen
in the desert.
Firstly, it’s all about finding water and
retaining it.
Succulents, called so for their juicy inside,
like cacti and desert aloe have extra-large
vacuole storage in their inside for water
storage.
A thick layer of wax called a cuticle shields
the outside of succulents from water loss,
while many succulents also have sharp thorns
to deter thirsty predators.
The saguaro cactus, in fact, does not have
deep roots to tap into water deep underground.
It simply waits out the drought, even if that
means sitting and baking in the sun for a
couple years.
The Mesquite tree has a totally different
approach, poisoning nearby trees with its
side roots and drilling down over 200 feet
to tap into underground water with its deep
roots.
Crassulacean Acid Metabolism, or ‘CAM’
for short, means these plants only open their
stomata--the site of plant-gas exchange for
Carbon Dioxide and Oxygen--in the cooler night
to avoid too much water from being evaporated
out from open stomata during the hot day.
However, water retention is not the only strategy
desert plants use.
Many desert non-succulents do not even have
specialized vacuole storage.
Instead, some have narrow leaves, which don’t
become heated as much from the sun or lose
water as fast as large, flat leaves.
Palisade cells--cells which have many chloroplasts
for photosynthesis--are also more densely-packed
in the leaves of many desert non-succulents
to maximize photosynthesis in a more narrow
leaf area.
As with succulents, though, nonsucculents
have waxy cuticles and CAM metabolism.
There’s even a tumbleweed called ‘the
resurrection plant’, which dries up and
is tossed around by the wind until rain comes.
It can roll around in its dry state for 100
years, and water makes it swell up, unfurl,
and begin seeding new seedlings within minutes,
after which the dryness makes it and its offspring
shrivel up again to repeat this process.
All sorts of unique adaptations may be seen
simply by examining the abilities of desert
plants.
Hopefully now a cactus doesn’t just seem
like a big, senseless ball of spikes, and
hopefully we’ll never have to see a world
where the only plants able to live are cacti.
