Seed Plants Outnumber seedless plants 10 to 1 They are food—rice, peas, squash They make materials like clothes, furniture and oxygen.
Characteristics of seed plants • Have vascular tissue—with true roots, stems and leaves • Reproduce with pollen and seeds
Vascular Tissue • Transports materials throughout the plant and helps support the plant. • 2 types: • phloem—transports food • xylem- transports water and minerals
Pollen and seeds • Seed plants produce pollen that contain cells that will later become sperm cells. • Once the sperm cells fertilize the egg cells a seed develops.
Seeds • Three main parts : • Embryo-this is the young plant that develops from the zygote (fertilized egg). • Cotyledons—seed leaves that can store food. • Seed Coat-outer covering of the seed which protects the embryo
Seed Dispersal • Animals may eat the seed then “release” it somewhere else. • The seed itself may have a structure that aids in dispersal such as barblike structures, velcro or even wings like a maple tree seed or dandelion. • Water can disperse seeds—seed simply floats to another area. • Some plants have an ejection system like a “touch me not”
Germination • When a seed begins to grow is germination. • The seed must have water and use the stored food to begin to grow. When you can see the first leaves of a plant you call it a seedling. • Seeds that are dispersed far away from the parent plant do better because of lack of competition for sunlight, water and minerals.
Order of reproduction • Pollination • Fertilization • Germination
Roots Functions • Anchors plant to ground • Absorbs water and minerals • Sometimes stores food
Types of roots • Fibrous—a dense tangled mass of similarly sized roots. Ex: grass or onions • Taproot—one long main root to which smaller roots branch off of. Ex: carrots or dandelion
Structure of the root • Root Cap—the rounded tip of the root. It protects the root from injury. • Root hairs—tiny hairs that grow out of the roots surface to go into smaller areas around the root to absorb water. They can also help anchor the plant into the soil. • Vascular tissue, both xylem and phloem, are located inside the root.
Function of Stems • Carries substances between the roots and the leaves • Provides support and holds up the leaves so they are exposed to the sun.
Structure of the Stem • Herbaceous—contain no wood—EX: daisy or pepper plant • Woody-rigid and hard like wood—EX: rosebush and trees • Both types contain xylem and phloem. • Woody also contains bark as the outermost layer. It also contains a layer of cells called cambium which divide to produce new phloem and xylem. • Annual rings a pair of light and dark rings on a tree stump. The wide light color are growth from spring while the thin dark color is from summer.
Leaves • Function—capture the sun’s energy • Structure—xylem and phloem are located between the layers of cells. The surface layers have small openings called stomata from which CO2 enters and O2 and water vapor exit. • Place where photosynthesis, cellular respiration and transpiration take place.
2 main groups • Gymnosperms-produce seeds that are “naked”—not enclosed by a fruit. • Angiosperms-produce seeds that are enclosed in fruits and also produce flowers.