2. Plant Adaptations (21.1, 22.4, & 22.3) State Standard
SB4E. Relate plant adaptations, including tropisms, to the ability to survive stressful environmental conditions.

3. Acts as a barrier to invading microorganisms
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

4. Openings in the outer cell layer of leaves and some stems
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

5. 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.

6. Vascular Tissues – 2 Types
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

7. 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.

8. Flowers can be pollinated by wind, insects, birds, & other animals
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

9. 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

10. 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.

11. 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

12. Reproductive Adaptations
Seed Dispersion
Coconuts from palm trees float which allows seeds to travel from one island to another

13. 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 needle-like leaves to conserve water and flexible trunks to bend & not break under the weight of ice & snow

14. A tropism is a plants growth response to an external stimulus.
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

15. Tropisms
Phototropism is a plant growth response to light caused by an unequal distribution of auxin.

16. Gravitropism is a plant growth response to gravity (AKA Geotropism)
Tropisms
Gravitropism is a plant growth response to gravity (AKA Geotropism)
Roots usually show a positive Gravitropism
Stems show a negative Gravitropism

17. Tropisms
Thigmotropism is a growth response to mechanical stimuli such as touch

18. 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

19. 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

20. Types of Plant Hormones
Gibberellins
Cause plant to grow taller
Increase rate of seed germination & bud development

21. Types of Plant Hormones
Abscisic Acid
Inhibits plant growth during times of stress, such as cold temperatures or drought