State Standard

SB4E. Relate plant adaptations, including tropisms, to the ability to survive stressful

environmental conditions.

Plant Adaptations(21.1, 22.4, & 22.3)

Cuticle

Introduction to Plants

Fatty coating that helps prevent the evaporation of water from plant tissues

Acts as a barrier to invading microorganisms

General Plant Adaptations

Chapter 21

Stomata

Introduction to Plants

Adaptations that enable the exchange of gases even with the presence of a cuticle on a plant

Openings in the outer cell layer of leaves and some stems

General Plant Adaptations

Chapter 21

Vascular Tissues

Introduction to Plants

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.

General Plant Adaptations

Chapter 21

Vascular Tissues – 2 Types

Introduction to Plants

General Plant Adaptations

Chapter 21

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

Flowers

Introduction to Plants

Reproductive Adaptations

Chapter 21

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

Cones

Introduction to Plants

Reproductive Adaptations

Chapter 21

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

Seeds

Introduction to Plants

Plant structures that contain an embryo, nutrients for the embryo, and are covered with a protective coat

These features enableseeds to survive harsh environmental conditions and then sprout when favorable conditions exist.

Reproductive Adaptations

Chapter 21

Reproductive Adaptations

• 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

Seed Dispersion

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 needle-

like 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