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| The Magnificent Plant Kingdom |
August 24th, 2003.
By Professor Fabio Cupul
Permanent Member of SOMEDICYT, the prestigious Mexican
Society for the Dissemination of Science and Techniques. |
In the last issue I mentioned the
existence of five kingdoms: plants, animals, fungus,
protozoa and bacteria. However the discussion continues
with regard to the inclusion of a sixth kingdom: the
virus. Viruses are extremely small, in fact 10,000 of
them (like the cold virus) can easily fit on the head
of a pin.
Simply stated, it is possible to
define viruses as a portion of genetic material protected
by a layer of protein. The reason why the debate goes
on with regard to categorizing them in a kingdom is
because they cannot be classified as “living beings”,
as they cannot feed or grow, they cannot reproduce by
themselves, but everyone knows that by inserting genetic
instructions in a guest cell, it may be forced to make
more viruses. Once the viruses penetrate the cells,
they can cause diseases in humans like the common cold,
rabies, polio and AIDS.
Now that we’ve cleared up that
point, we go on to analyzing the marvelous facts we
can observe in the fascinating kingdom of plants. One
of them is what happened when a 3,400-year old seed
was discovered in the tomb of the famous Egyptian pharaoh
Tutankamen. The fact was not that the seed was found,
the marvel was that the seed sprouted after such a long
wait.
Nevertheless this is not a record
waiting period when we compare it to the 10,000 years
a species of legume seeds waited to germinate, until
they were discovered by a Canadian miner, frozen in
the Arctic. Once they were thawed, they produced perfect
adult plants.
One fascinating aspect about some
plant species is their tendency to devour animals. It
is wrong to think that they are eager to consume great
chunks of meat to satiate their voracious appetite,
in fact, they have no teeth with which to bite and chew,
nor a stomach in which they might digest the food. What
they do is capture the animals alive using elaborate
and astute gimmicks, and then absorb the vitamin and
mineral nutrients of their bodies.
One of those “carnivorous plants”
is the Nephentes that has devised elaborate jar-like
structures at the tip of their leaves, filled with a
sweet-smelling liquid. Attracted by the scent, insects
land on the edge of the plant where they can find drops
of a liquid that resembles honey, secreted by the plant
so that they will stay there. Once the insect begins
to look for more food, it quickly loses its balance
and falls into the liquid. The slippery spiny walls
of the leaves ensure that the prey cannot flee. The
insect drowns and is digested by the liquid in the “jar”.
“Carnivorous plants”
only use the nutrients extracted from the animals as
a food supplement, as they continue executing their
normal photosynthetic work to synthesize their food
through the sun. Also, the traps used by those plants
are minute, just a few centimeters in size, so the preys
found on their menu are generally small insects.
But not everything in the plant kingdom
was conceived on a small scale. There are true giants
there as well. Among those giants are the Sequoias that
weigh in around 5,000 tons each and grow to heights
greater than 300 feet. They are probably the largest
and heaviest living beings to have ever lived on earth.
Some are more than 3,000 years old and their trunks
can measure 40 feet in diameter at the base, while their
roots can take over a surface larger than a football
field.
Today, those conifers have been reduced
to 75 groves that survive in the mountains of the Sierra
Nevada, in northern California. At the time of the colonization
of the American West, four woodsmen would have to work
for 22 days just to cut down one of those trees. It
would supply enough wood to build a small town. Today,
the giant sequoia are protected in the national parks
and forests of the areas they inhabit.
Finally, it would seem that plants
just stand there unprotected on the earth, without any
weapons that would enable them to defend themselves
against predators or other dangers. However there is
nothing further from the truth. In the case of the cactus
for example, their fleshy trunks are covered with sharp
spines that stop hungry animals from approaching them.
Furthermore, at the base of the spines,
the plant also has some golden brown tufts of hair.
Those hairs with pointy ends come off easily when touched
and slowly penetrate the skin of the animal, causing
an extremely unpleasant feeling that lasts for days.
Once they’ve confronted those spines and hairs,
mammals such as deer looking for food avoid getting
close to consume its fruit.
Vallarta’s Nature Field Guide -
File 4
Virginia Opossum
 Whenever
we speak of those animals that have a ventral pouch
of skin called marsupio (thus the name marsupials) that
consists of a cutaneous pouch present only in females
(the male has a rudimentary marsupio) whose function
it is to protect and feed so that the offspring may
complete their embryonic and post-natal development,
inevitably, we immediately think of the Australian continent
and its kangaroos.
But that is not the only continent
to safeguard the representatives of this group. Our
region is home to one very American marsupial: the tlacuache
or Virginia Opossum (Didelphis virginiana). Tlacuaches,
as we call them, are animals that live mostly in tropical
regions. They have five fingers on each hand with an
opposable thumb, something reminiscent of a human hand.
They are active at night and prefer to do so in trees
as they move very slowly on land.
One of its outstanding characteristics
is its way of defending itself from predators, considering
that it lacks active means of defense, is to pretend
it is dead. They have few enemies due to the foul odor
of their skin. When they become aggressive, they secrete
a most foul odor through their anal glands. Its diet
is made up mostly of insects, small invertebrates, carrion,
fruit and a varied selection of plants.
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