Plant Adaptations By Moira Whitehouse PhD

Plant Adaptations
By Moira Whitehouse PhD
What do plants need to survive?
• sunlight
• carbon dioxide
Ingredients for
photosynthesis
• water
• the right temperature
• protection
• to reproduce
What part of the plant absorbs water?
a
b
c
e
d
Why do plants have flowers?
Many plants use
flowers to
spread pollen
(genetic
information) to
other flowers.
They also use
colors and
smells to attract
insects, to help
plants spread
their pollen.
Plant Roots
Roots are very
important. This is where
plants absorb WATER
and NUTRIENTS.
Roots also keep the
plant grounded – they
keep the plant from
falling down. The bigger
the plant or tree, the
thicker the roots need to
be!
Why do plants need stems?
Plants use stems
to support the
leaves and
flowers – TO HELP
THE PLANT STAND
UP!
The stem usually
grows in the
direction of
sunlight – plants
can make more
food if they can
absorb more
sunlight!
The stem has the xylem
Plants need a way to carry
water and nutrients from
the roots up to the leaves
and flowers.
Complicated animals have
a circulatory system to
move blood (which has
water and nutrients in it).
Plants don’t have this, so
they have the adaptation
of the xylem instead.
Plant Leaves – Top Part of the Leaf
The top part of the
leaf is where the
plant makes food
(glucose). We call
this process
photosynthesis.
The leaf has lots of
chloroplast which
absorb the sun’s
energy. The
chloroplast use this
energy to make food
for the plant.
Plant Leaves – Bottom Part of the Leaf
The bottom part of the leaf
does not get very much
sunlight.
Instead of making food, this
is where the plant
“breathes”.
There are holes (pores)
under the leaf where the
plants take carbon dioxide
(CO2) from the air.
Water vapor (H2O) also
escapes out from these
holes. Plants try to reduce
this water loss as much as
possible.
Morning Dew – misty day
When water vapor escapes from the bottom of the leaf, it helps
cool the plant down. Plants lose more water on hot days, and
less water on cool days. If plants lose too much water, they can
dry out and die. They try to reduce this water waste as much as
possible.
a
b
c
e
d
What part of the plant is involved in
reproduction?
a
b
c
e
d
Carbon dioxide is generally available to
most plants from the air surrounding them.
Sunshine is also generally available but in
some cases plants have actively seek it:
Plants that live in dense forests do have
to compete for light.
Noting that most plants grow towards the
light, consider the these cases:
Many trees in
the forests
grow very tall to
get to the
sunlight.
Some rainforest
plants climb on
others to reach the
sunlight.
Plants that live on the forest floor are adapted
to live in the shade and require less sunlight.
Next, we consider a plant’s need to reproduce?
To protect themselves, plants cannot run away
from animals that want to eat them, such as
deer, goats, bears, insects, and rabbits. But
many plants do have ways to protect
themselves.
Some plants taste
bitter.
Some plants have
thorns on their leaves
or stems.
Some plants are poisonous and cause a
rash on an animal’s skin. You may be
familiar with the rash caused by poison
ivy.
A plant gets water through its roots and
loses water through its leaves .
Many of a plant’s adaptations have to
do with getting and retaining water.
Most plant adaptations seem to have come
about because of the plant’s water supply.
The rest of this presentation will be about
how plants have adapted in the regions of
the Earth that are defined largely their
temperature and by how much or how little
water they normally get.
We will consider plant adaptations in:
1) deserts, 2) grasslands, savannas, prairie
and steppe grasslands, 3) forests, rain,
deciduous and coniferous and 4) the Tundra.
First, some plant adaptations found in
Desert plants.
The desert regions shown in brown are dry and
generally hot, and often have poor soil that holds
little water.
Plants in deserts
usually have a
large, shallow root
system.
This means the
roots are spread
out wide and
absorb a lot of
water when it does
rain. The roots do
not grow very
deep.
Question: In the desert, why is it better to have
shallow roots than roots that grow deep?
Remember: shallow means the roots stay close to the surface and don’t grow very deep
below the ground.
Desert plants
often store
water in their
stems or leaves.
Cactuses have
stems but no
leaves.
A waxy
coating on
the leaves
or stems
reduce
loss of
water.
Hair or spines
help shade the
plant so it does
not lose so much
water.
Deep root
system or
Next, some plant adaptations found in
Grassland plants.
The grassland regions can be divided into
Savannas (tropical grassland) shown here in
yellow which generally have a warm climate and
always have definite wet and dry seasons, and:
the prairie and steppes regions of the Earth.
These regions, shown here in yellow have mainly
dry weather, deep fertile soil, and are usually hot
in the summer and cold in the winter.
Roots of
grassland/prairie
grasses extend deep
into the ground to
absorb as much
moisture as they
can.
Grassland/
prairie
grasses
have
narrow
leaves
which lose
less water
than broad
leaves.
Baobab tree in African
grassland has huge
trunk to store water
during the dry season
Next, some plant adaptations found in
the forests of the world.
There are three forest regions. The Tropical Rain
Forests shown here in dark green which seldom
get below 68 degrees, get about 100 inches of rain
each year and have less than one inch of top soil.
Tropical rainforest trees have shallow
roots because the soil is so thin.
Buttresses and stilt roots help prop up
plants in the shallow soil.
Many rainforest leaves have “drip tips”—a
pointed shape which helps drain excess
water from the leaf.
Epiphytic orchids have
aerial roots that cling
to the host plant.
They absorb minerals,
and water from the
atmosphere.
Continuing with plant adaptations found in
the forests of the world.
The deciduous Forests shown here in dark green,
have four seasons with rain in the summer and
rain or snow in the winter.
The temperature varies from hot in the
summer to below freezing in the winter.
Rain is plentiful, about 30 to 50 inches per
year but the trees become dormant in the
winter when there is less water available.
In both the tropical rain forest and deciduous
forest the trees have
to absorb as much sunlight as possible.
Water loss through these big leaves is not a
problem because these regions normally get
adequate water.
BIG LEAVES
The thin, broad, light-weight leaves of the
deciduous trees can capture a lot of sunlight to
make a lot of food for the tree in warm weather.
Most deciduous
trees have deep
spreading roots—
as wide as the
canopy.
When the weather gets cooler, the broad leaves
cause too much water loss and can be weighed
down by snow, so the tree drops its
leaves. New ones will grow in the spring.
Continuing with adaptations found in the
forests of the world we consider the coniferous
forest shown here in dark green. These
regions have short summers and long cold
winters.
Temperature not hot in the summer but
very cold in the winter. Moisture is
generally good in the spring and summer,
but freezes and is not available for the
plants in the winter.
Long roots to hold up tall trees.
Needle-like
leaves with waxy
covering help
reduce water loss
during freezing
weather.
They do not drop leaves
(needles) all at once in fall.
They are kept throughout the
year to make food whenever
sunshine and water are
available (short summers).
The triangular shape of many conifer
trees helps shed heavy snow to save
branches from breaking.
Finally, we consider plant adaptations found
in the Tundra shown below in brown. This is
a vast, flat, treeless Arctic region of Europe,
Asia, and North America in which the subsoil
is permanently frozen.
These tundra plants are
low-growing to avoid
the harsh winds.
This plant grows
in a clump to
help conserve
heat.
Shallow roots to absorb the limited water.
In conclusion, we have touched on just a
tiny sample of the remarkable adaptations
plants around the world have made in order
to survive. The thing to remember is that
plants, as well as animals, must satisfy their
needs in order to survive, they have to
adap
t
to conditions in their environment.