Transcript Plant Adaptation Notes

Plant Adaptations
(21.1, 22.4, & 22.3)
State Standard
SB4E. Relate plant adaptations, including
tropisms, to the ability to survive stressful
environmental conditions.
Chapter 21 Introduction to Plants
General Plant Adaptations
Cuticle
 Fatty coating that
helps prevent the
evaporation of water
from plant tissues
 Acts as a barrier
to invading
microorganisms
Chapter 21 Introduction to Plants
General Plant Adaptations
Stomata
 Openings in the
outer cell layer of
leaves and some
stems
 Adaptations that
enable the exchange
of gases even with the
presence of a cuticle
on a plant
Chapter 21 Introduction to Plants
General Plant Adaptations
Vascular Tissues
 Vascular tissue enables faster movement
of substances than by osmosis and
diffusion, and over greater distances.
 Vascular tissue provides support and
structure, so vascular plants can grow
larger than nonvascular plants.
Chapter 21 Introduction to Plants
General Plant Adaptations
Vascular Tissues – 2 Types
 Xylem – carries water &
dissolved minerals from
the roots upward to the
stem & leaves
 Phloem – food-carrying
tissue. Carries sugars &
other organic
compounds throughout
the plant
Chapter 21 Introduction to Plants
Reproductive Adaptations
Flowers
 Flowers are the
reproductive structures
of a group of plants called
anthophytes.
 Flowers contain both
male parts (stamens) & a
female part (pistil).
 The movement of pollen
from a stamen to the pistil
is called pollination.
Reproductive Adaptations - Flowers
• Flowers can be pollinated by wind, insects, birds, &
other animals
• Many flowers are brightly colored to attract birds &
insects that aid in pollination
Chapter 21 Introduction to Plants
Reproductive Adaptations
Cones
 Cones are the reproductive
structures of a group of
plants called conifers
(coniferophyta).
 Conifers produce small male
cones & larger female cones.
 The male cones produce
pollen while the female
cones remain on the plant
until its seeds have matured.
Male Female
Chapter 21 Introduction to Plants
Reproductive Adaptations
Seeds
 Plant structures that
contain an embryo,
nutrients for the embryo,
and are covered with a
protective coat
 These features enable
seeds to survive harsh environmental conditions and
then sprout when favorable conditions exist.
Reproductive Adaptations
Seed Dispersion
• Maple trees produce seeds that are shaped like
wings & are carried over long distances by wind.
• Some plants produce seeds with barbs or hooks
that attach to the fur of passing animals
Maple Seed
Reproductive Adaptations
Seed Dispersion
•Coconuts from palm trees float which allows seeds
to travel from one island to another
Other Plant Adaptations - Dormancy
• Many seeds & plants will go dormant (inactive)
during unfavorable conditions such as drought or
cold
• Some roots & stems are able to store food for
dormant periods
• Some trees drop their leaves during dormancy
• Other trees (such as conifers) have waxy needlelike leaves to conserve water and flexible trunks to
bend & not break under the weight of ice & snow
Tropisms
• A tropism is a plants growth response
to an external stimulus.
– If a plant grows toward the stimulus it is
called a positive tropism
– If the resulting plant growth is away from
the stimulus it is called a negative tropism
Tropisms
• Phototropism is a plant growth response to
light caused by an unequal distribution of
auxin.
Tropisms
• Gravitropism is a plant growth response to
gravity (AKA Geotropism)
– Roots usually show a positive Gravitropism
– Stems show a negative Gravitropism
Tropisms
• Thigmotropism is a growth response to
mechanical stimuli such as touch
Plant Hormones
• Plants control their growth in response to
environmental stimuli by using chemical
messengers known as hormones
• A hormone is a chemical produced in one part of an
organism that is sent to a different part of the
organism to affect activities there
Types of Plant Hormones
Auxin
• Controls phototropism by elongating cells on the
shaded side of the stem to push the plant toward
light
• Promotes growth of fruit and controls when the
fruit falls from the plant
Types of Plant Hormones
Gibberellins
• Cause plant to grow taller
• Increase rate of seed germination & bud
development
Types of Plant Hormones
Abscisic Acid
• Inhibits plant growth during times of stress, such
as cold temperatures or drought