We already know that plants
need water to be able to
conduct the process of
photosynthesis but what we
don’t know is how the water
travels within the plant.
First of all we need to know how the water
gets into the soil. This is an easy one – Rain.
When it rains, the water gets soaked up by
the soil. Plants can also absorb water that has
built up from rain water or ground water.
Absorbing the water
The roots of plant do not actually reach down into the soil to find water reserves,
and plants don't sip water through roots like straws. Instead, the hundreds of
hairs that extend from the tip of every root absorb water from the soil. The roots
themselves mainly serve to anchor the plant firmly in place and channel the water
Even in seemingly dry soil, a thin film of water surrounds every microscopic soil
particle. As the roots grow, the hairs, which are actually single cells, stretch out
and absorb the film. The water diffuses through the cell walls, and gets drawn up
into the roots.
The root’s other job
The cortex of the root is divided up by sheets of cells called
vascular rays, which carry water laterally to the center of
the root which is the called the stele. Inside the stele are
veins that serve as the circulatory system of the plant. Here
is where the water begins its journey upward and into the
The vein that conducts water from the stele is called the xylem.
The xylem extends to every part of the plant. It is made up of
columns of dead reinforced cells that move the water and mineral
from the roots through the stem to the leaves. Xylem cells make
a tube from the leaf, down the stem to the roots. In the root it
has to resist forces that could pull the plant out of the ground. In
the stem it has to resist compression and bending forces caused
by the weight of the plant and the wind.
Transpiration explains how water moves up the plant against
gravity in tubes made of dead xylem cells without the use of a
pump. The water that a plant uses serves several functions. In
addition to hydrating and nourishing the plant, it also regulates
the plant's temperature. This is called transpiration. The warmth
of the sun causes the water on the surface of spongy and palisade
cells (inside the leaf) to evaporate and then diffuse out of the
leave. As the plant becomes warm, more water is drawn out of the
xylem cells making a continuous tube from the leaf, down the
stem to the roots.
Xylem & Phloem
The xylem and phloem are located side-by-side in plants;
the xylem is near the outside of the plant structure,
while the phloem is closer to the inside. They basically
make up the vascular system of the plant.
I have already talked about xylem so here is what phloem
does. During the process of photosynthesis, the water
dissolves the glucose (sugar) made in the leaves. This
sugar-water is carried from the leaves back down the
plant toward the roots through another vein, called the
phloem. It feeds every part of the plant as it travels
1 - "BBC - GCSE Bitesize: Transpiration." BBC - Homepage. Web. 10 Mar. 2011.
2 – "How Is Water Transported From the Roots Throughout Plants? | Garden
Guides." Garden Guides, Your Guide to Everything Gardening. Web. 10 Mar. 2011.
3 - Martinez, Jessica. "How Is Water Transported From the Roots Throughout
Plants? | EHow.com." EHow | How To Do Just About Everything! | How To Videos
& Articles | EHow.com. Web. 10 Mar. 2011. <http://www.ehow.com/how-