Plants and Their Adaptations Variations of Parts Roots Leaves Seed Dispersal Attraction of Pollinators Phototropism Geotropism

Survival  As you watch this presentation, focus on how variations, adaptations, or behaviors enhance a plants’ survival. Include: Roots Seeds Stems Phototropism Leaves Geotropism Flower

Variations o Variation is: – the difference between individuals of the same species – the process or act of changing o Variation is necessary: – If all of the plants in a species were exactly the same, they could all be taken out by disease or disaster.

Structure and Function Comparing structure and function of parts and behaviors helps us understand why variation is necessary.  Structure is the form of an organism’s parts.  Example: A pedal is structured like a landing strip for insects.  Function is what that part does.  Example: The function of a petal is to attract insects.

Common Plant Parts  Most plants, no matter how they look, share some common parts.  Most plants have:  Roots  Stems  Leaves  Flowers commons.wikimedia.org/wiki/File:Leaves-scan.jpg

Structure and Function  The structure and function of plant parts show evidence of adaptation.  Examples Include:  Defenses against consumers  Ways to attract pollinators  Seed dispersal to ensure survival

Roots Roots must adapt to their different environments. Structure and Function: – Roots act as anchors to keep plants grounded. – Roots take in water and minerals from the soil through tiny root hairs. – Some roots can store food.

Roots Some roots spread out along the ground in search of water in places where it rains often.

Some roots grow deeper into the ground in search of water in places where the climate is dry. Roots

Roots Some roots begin on a stem rather than below the ground. They are used for support to prop or brace the plant. Roots Soil

Roots Some plants are able to store food in their roots for later use. These are called storage roots.  Some examples include:  sweet potatoes  carrots  beets  radishes

Stems Stems must adapt to whatever environment the plant is in. o Functions: – Hold the plant upright and support the leaves – Carry water up the plant and food down from the leaves to other parts of the plant – Defend plants: thorns, prickles, and stinging hairs

Stems Many stems are edible like asparagus, broccoli, cauliflower, and celery. Cinnamon: The bark is used as a spice. Garlic and Onion: They are bulbs. Ginger Root: The edible portion is a branched underground stem called a rhizome. Potato: The edible portion is an underground stem that is also a tuber. Sassafras Tree: The shoots and stem bark can be used to make root beer.

Leaves Leaves have many shapes and sizes, all depending on the environment and how much sunlight the plant needs.

Leaves  Functions:  Make food through photosynthesis and release oxygen  Protect the plant: prickles and spines

Leaves Notice how some leaves have adapted to function as a defense.

Flowers  Functions:  A flower helps the plant reproduce.  The flower contains the pollen and egg necessary to make a fruit which has the seeds in it.

Structure of a Flower

Seeds  Seeds disperse differently depending on their structure:  Wind: Flowers can have a wing-like structure.  Water: Flowers can have water-proof covering.  Animals/Humans: Flowers can have burrs for sticking to fur or clothing.  Insects: Pollen sticks to insects as they move from place to place.  Some seeds can split and twist to throw seeds in all directions.

Seeds Wind: Maple seeds have a wing-like structure. Insects: Pollen sticks easily to this bumble bee.

Seeds Animals: This bison’s face is covered in cockleburs, which are the Velcro ® -like seed pods. Water: The Heritiera littoralis seed has a water-proof covering.

Phototropism Directional growth in response to the direction of the light source. o Positive Phototropism: growth towards a light source – Plant shoot leaves exhibit positive phototropism o Negative Phototropism: growth away from light source – Roots usually exhibit negative phototropism.

Geotropism Turning by a plant in response to gravity o Charles Darwin documented the following: –Stems show negative geotropism (grow in opposite direction of gravitational pull) –Roots show positive geotropism (grow in direction of gravitational pull)

Sweet Potato Plant This plant was sprouted in a shallow bowl of water in a kitchen. The leaves on the main sprout were facing the window and are reaching toward the light. The leaves on the secondary sprouts are bending toward the light because they were facing away from the window. The roots are reaching downward toward the ground. They are filling the bowl but always trying to go downward.