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Symbiosis between the roots of a tree and a
fungus
Did You Know?
The roots of 80% of all plants are
covered by fungal hyphae. The
plants are not sick, however, but
rather live in a tight biotic commu-
nity with the fungus. The fungus
takes water from the ground and
passes it on to the plant, and the
plant supplies the fungus with nutri-
ents. By virtue of the entanglement
of fungal hyphae, the root surface
is increased 100- to 1000-fold — a
great deal for the plant! Such living
arrangement between fungus and
plants are called mycorrhiza.
Conduction vessels can be constructed in very
different ways, but what they have in common
is always a cell wall reinforced with rings and
ridges.
result, then simply press on the cover slip carefully with the butt end of a pen.
The root will be pressed flat a bit by this. The root hairs at the edge of the root
will not be harmed much by this. Root hairs are actually protuberances of a cell
in the outermost layer of a root. If you start searching at the tip of the root,
you won't find any root hairs at first. The so-called root hair zone only begins
a bit above the tip. At first, only cells with small recesses are visible, but as you
move away from the tip, they become longer and longer and finally grow into
root hairs of varying length.
From the Root into the Melon
The cell walls of the root hairs are so tender that the water is able to pass
through them into the cells of the root. But how does the water then travel to
the other parts of the plant? Transporting the water from cell to cell would not
only be tedious but also much too slow. Just as there are veins in humans to take
care of transporting the blood (and hence water), there are specialized vascular
ducts in plants too — the so-called vessel cells (tracheary elements and tracheids).
They extend from the root through the entire plant and into every leaf, blossom,
and fruit (i.e. into the watermelon).
The amazing thing about these ducts is that the cells from which they are con-
structed die off before the water duct operates. As soon as water flows through
them, nothing is left of the original contents of the cell. Only the cell walls
remain as a sort of water pipe. To stabilize the tubes, ring- or screw-like reinforce-
ments are also present.
Water Ducts in the Melon
It's easiest to go ahead and get water ducts directly from a watermelon. You
will need:
• a slide and a cover slip
• the pipette and water
• the tweezers
• a piece of watermelon
If you take a close look at a piece of watermelon, you can see light-colored,
twisting lines in the red flesh. These are the water ducts that have transported
the water from the root into the melon. Using the tweezers, pluck a little
piece of one of these ducts and dab it in a drop of water on a slide. The same
thing applies here as before: If the plucked preparation is a bit too thick, sim-
ply press down carefully on the cover slip with the end of a pen. An examina-
tion of the object reveals the various types of vessels with their ring-shaped or
spiral-shaped structures.
Conduction vessels from a pumpkin stem
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