Transcript Plant Structures

Structure
and Function
In Different Environments
Introduction
 Plants
have various structures that help them to
survive in different environments.
 In
this presentation, we will look at the adaptations
in the structures of plants, including roots, stems,
and leaves of plants in different environments.
 We
will compare the structure and function of plant
parts from the following environments: desert,
wetlands, forest, and tundra.
Desert- A Definition
A
desert is a region that receives an
extremely low amount of
precipitation (rain or snow), less than
enough to support growth of most
plants.

Plants lose a lot of moisture through
a process called transpiration. (Sort
of like a person losing water through
perspiration.)
 Deserts
can be hot or cold.
Wetlands- A Definition
A
wetland is an area
between a land-based and
a water-based ecosystem.
 Wetlands
include bogs,
fens, marshes, and swamps.
 Although
there are many
different types of wetlands,
they have three physical
characteristics in common.
Wetlands- A Definition
 Water – Wetlands are covered with shallow
water for at least some time during the year.
 Soil – The soil often has little or no oxygen.
 Plants – Wetlands provide habitat for “water-
loving” aquatic plants (hydrophytes). These
plants are adapted to living in saturated
(really full of water) soil all or part of the year.
Tundra- A Definition
 The
word "tundra" usually
refers only to the areas
where the subsoil is frozen
all the time (permafrost).
 The
plants in this
environment include
shrubs, sedges, grasses,
mosses, and lichens.
Forest- A Definition
 A forest, or woods, has many trees.
 There will usually be an upper tree
layer (canopy) and the understory.
 Other plants, such as shrubs, vines,
flowers, and mosses, are found in
forests.
 Forests can include
rainforests, boreal
forests, and conifer
forests.
Roots
 The
four major functions of
roots are:




Absorption of water and
nutrients (food)
Anchoring the plant to the
ground
Storage of food and
nutrients
To prevent soil erosion
 Buttress
roots are large
roots on all sides of a tree
with a wide base or a tree
with shallow roots.
Roots: Dry Environment
 Some
desert plants
have long taproots
that go all the way
to the water table, if
present.
 Some
desert plants
have adapted to
the weather by
having widespreading roots, to
absorb water from a
greater area of the
ground.
Roots: Wetland Environment
 Emergent
– Rooted in
soil, but plant parts
extend above the
water
Submergent – The
entire plant lives
underwater.
Roots: Wetland Environment
 Floating
– Leaves
float on the surface,
while roots hang
down into the water
or are planted in the
soil
 Riparian
– Found
along the edges of
wetlands or other
water bodies
Roots: Tundra Environment
 There
are no deep root systems in the plants
(vegetation) of the arctic tundra.
 Many
plants have rootlets (rhizoids) instead
of roots.
Stems
A
stem is the part of the plant that usually grows
above the ground and holds the leaves.
 The
stem has four main functions:

Supports and elevates the plant, leaves, flowers, and
fruits

Transports fluids between the roots and the shoots

Stores nutrients

Produces new living tissue
Stems

Some plants have thorns
on their stems for
protection.

Some plants have stems
that wrap around other
plants or structures. This
provides a way to support
the plant as it grows.
Stems

The stems of many desert
plants feel “waxy”. Some
desert plants store water
in their leaves, roots, and
stems.

The stems of tundra
plants are often very
short. Plants grow close to
the ground in this
environment. Tundra
plants do not have
woody stems.
Stems
 The
stems of many
aquatic plants are
flexible.
 Flexible
stems move
easily in water currents.
Leaves
 The
shape and structure
of leaves varies
considerably from plant
to plant.
 The
main purpose of
leaves is to produce food
(energy).
 Another
purpose of a leaf
is to get carbon dioxide
from the air (atmosphere)
to make sugar and
release oxygen.
Leaves: Dry Environment
(desert)
 Desert
plants often
have small, spiny
leaves.
 They
are designed to
reduce water loss in
the plant.
Leaves: Temperate Environment
(forest)
 Some
trees have broad
leaves that absorb water
and sunlight.
 Some
trees have
“needles” for leaves. The
needles’ shape and waxy
coating help the plant
conserve water during the
cold winter and in hot
climates.
Leaves: Tundra Environment
 Tundra
plants have very
tiny leaves.
 There are usually many
leaves on one stem.
 Sometimes the leaves
appear to be “wooly”.
Leaves: Wetland Environment
 Leaves
are usually
round and flat or
long and thin.
 The flat leaves float
on the surface.
 The thin leaves
move easily when
water flows.
Special Structures…
 Carnivorous
plants have
adapted to living in the lownutrient areas of wetlands
(bogs and fens) in a special
way.
 They
have structures that allow
the plant to trap and digest
insects. The insects provide
the necessary nutrients that
they cannot obtain from the
soil.