Chapter 8 Section 3

1. Chapter 8 Section 3 The Characteristics of Seed Plants

2. What is a Seed Plant? • Seed plants outnumber seedless plants • Produce much of the oxygen we breathe • All seed plants have roots, stems, and leaves • The plants that you see are the sporophytes, the gametophytes are microscopic • 2 important characteristics • Vascular tissue • Use pollen and seeds to reproduce

3. Vascular Tissue • Helps support plants • Food, water, and nutrients are transported through the plant • Two types of vascular tissue • Phloem: tissue through which food moves • Xylem: tissue through which water and minerals move

4. Pollen and Seeds • Do not need water for sperm to swim to eggs • Instead, seed plants produce POLLEN • Tiny structures that contain cells that will later become sperm cells • Pollen delivers sperm cells directly near eggs…fertilization occurs…seeds then develop • Seed • A structure that contains a young plant inside a protective covering

5. How Seeds Become New Plants • Inside a seed is a partially developed plant • Seed lands in favorable area, the plant sprouts out of the seed and begins to grow • Seeds need light, water, and nutrients to grow

6. Seed Structure • Three main parts • Embryo • Young plant that develops from the fertilized egg (zygote) • Cotyledon • A seed leaf that sometimes stores food • Seed coat • Keeps the seed from drying out • Acts like plastic wrap • In many plants, the seeds are surrounded by a structure called a fruit

7. Seed Dispersal • Animals • Seeds pass through animal’s digestive system and are deposited in new areas • Barblike structures hook onto an animal’s fur • Water • Seeds that fall into oceans and rivers • Wind • Disperse light weight seeds (dandelions and maple trees) • Shooting out of a plant

8. Germination • Occurs when the embryo begins to grow again and pushes out of the seed • Seed absorbs water from environment • Seedling • When you are able to see a plants leaves • Better chance of living when seedling is far away from parent

9. Roots • Anchor a plant into the ground • Absorb water and minerals from the soil • Sometimes store food

10. Types of Roots • Fibrous root system • Similarly sized roots that form a dense, tangled mass • Take much soil with them when pulled out of ground • Lawn grass, corn, onions • Taproot system • One long, thick main root • Carrots, dandelions, cacti

11. The Structure of a Root • Root cap • Protects the root from injury during growth • Root hairs • Increase the amount of water and minerals absorbed by the root • Water and nutrients are absorbed from the soil and move quickly to the xylem • Phloem transports food manufactured in the leaves to the root

13. Stems • Carries substances between the plant’s roots and leaves • Support the plant and holds up the leaves so they are exposed to the sun

14. The Structure of a Stem • Two types • Herbaceous • Woody

15. Herbaceous • Contain no wood and are soft • Coneflowers and pepper plants

16. Woody • Hard and rigid • Outermost layer is bark • Cambium • Produces new cells which divide to produce new phloem and xylem • Sapwood • Active xylem that transports water and minerals • Heartwood • Old, inactive, xylem that provides support to • Maple trees and roses

18. Annual Rings • One year’s growth of a tree is represented by one pair of light and dark rings in the tree’s stem • Page 269

19. Leaves • Capture the sun’s energy and carry out the food-making process of photosynthesis

20. The Structure of a Leaf

21. The Leaf and Photosynthesis • Cells that contain the most chloroplasts are located near the leaf’s upper surface • Chlorophyll in the chloroplasts traps the sun’s energy

22. Controlling water loss • Transpiration • Process by which water evaporates from a plant’s leaves • Plants retain the water by closing the stomata