Warm Up Although ferns have vascular tissue, they still must live in moist, shady environments. Explain why.

Plants The Characteristics of Seed Plants Chapter 8 Section 3 Chapter 8 Section 3

Discover Activity Which plant part is it? Page 262

Objectives: To identify the characteristics that seed plants share. To explain how seeds become new plants. To describe the functions of roots, stems, and leaves.

Seed Plants Seed plants share 2 main characteristics: –Have vascular tissue –Use pollen and seeds to reproduce

Characteristics Seed plants are vascular plants that produce seeds. Vascular tissue is a system of tiny tubes that transport food, water, and other materials. Xylem carries water and minerals up from the roots through out the plant. Phloem carries food throughout the plant, both upward and downward. Seed plants have true roots, stems and leaves.

Conductive Vessel Element in Mountain Mahogany Wood (SEM x750). This image is copyright Dennis Kunkel at used with permission. Phloem TANAT.html

Seeds Seed plants do not require water to reproduce. The reproductive structures of seed plants are known as cones and flowers. Seed plants produce pollen which are tiny structure that contain the cells that will later become sperm cells.

A seed consists of a seed coat, a young plant, and stored food. The young plant is called an embryo. Germination is the early growth of an embryo plant (the one inside the seed).

Cotyledons are the seed leaves on the embryo. In some seeds, food is stored in the cotyledons. The seed coat protects the embryo so that the seed can inactive for a long period of time.

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Try This Activity The In-Seed Story page 264

Seed Dispersal Seed dispersal is the scattering of seeds, usually far from where they were produced. Look at the sample seeds and discuss how they are dispersed.

Germination Germination occurs when the embryo begins to grow again and pushes out of the seed. For this to happen the seed absorbs water from the environment and the embryo uses the stored food to begin to grow. The roots grow downward and the leaves grow upward.

Roots Roots provide several functions for the plant. They are –Anchor plants –Absorb water and minerals from the soil –Store food. Fibrous roots consist of several main roots that branch often. Taproot systems consists of a long, thick main root with thin roots coming from it.

Root Structure Root hairs are many thin, hair-like extensions that greatly increase the surface area through which the plant takes in water and minerals from the soil.

Root Structure The root cap is a structure that covers and protects the tip of the root as it grows. Just behind the root cap is a region that contains growth tissue, where new cells are formed.

Stems Stems provide the means by which water, minerals and food are transported and they support the leaves and other parts of the plant. Plants are divided into two categories based on the structure of their stems.

Stem Structure The parts of stems are bark, the outermost layer of a woody stem, cambium, a growth region where xylem and phloem are made, and pith, the center containing large, thin-walled cells that store water and food.

Woody are stems that contain wood; they are hard.

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Annual Rings The annual rings are made of xylem. During the spring the xylem grows rapidly and has a wide, light brown ring. During the summer it grows more slowly and produces a thin dark ring.

Herbaceous are stems that are green and soft.

Leaf Structure The outermost layer of a leaf is called the epidermis. They are covered by a waxy, waterproof coating that prevents excess water loss.

Leaf Structure Light passes through the epidermis to the mesophyll where photosynthesis takes place.

Leaf Structure Stomata are the guard cells that allow gases to enter and leave a leaf. They are located on the lower layer of the mesophyll.

Stomatal apparatus as seen on a leaf epidermal peel of corn. The above image is from gopher://wiscinfo.wisc.edu:2070/I9/.image/.bot/.130/Leaf/Corn_e pidermal_peel. Note the two sets of guard cells. gopher://wiscinfo.wisc.edu:2070/I9/.image/.bot/.130/Leaf/Corn_e pidermal_peel

Scanning electron micrograph of Equisetum (horsetail or scouring rush) epidermis. Note the oval stomatal apparatuses in the center of the stem. The above image is from ANAT.html

Pea Leaf Stoma, Vicea sp. (SEM x3,520). This image is copyright Dennis Kunkel at used with permission.

Photosynthesis occurs in the leaf and is the process in which food is made using light energy. It has two products glucose (food) and oxygen.

Photosynthesis Raw Materials –Carbon dioxide + Water Needed but not used up Sunlight and Chlorophyll End Products –Glucose + Oxygen

Leaf Structure Transpiration is the process in which water is lost through a plant's leaves

Observing Roots Carefully loosen the soil from the geranium and the other plant with a tap root. Have students examine and draw the root systems.

Actitivities Teacher Demo Try This Activity Teacher Demo

Lab Investigating Stomata

Homework