Characteristics of Seed Plants

EQ: How do I describe the function of leaves, stems, roots

and flowers?

Seed Plants • Most common type of plant on Earth

• All seed plants share 2 characteristics– Vascular

tissue– Use seeds to

reproduce

EQ: How do I describe the

function of leaves, stems, roots and

flowers?

Vascular Tissue

• Two types– Phloem – vascular tissue through which food

moves– Xylem – tissue through which water and

nutrient move

EQ: How do I describe the function of leaves, stems,

roots and flowers?

Seeds • Structures that contain a young plant inside a protective covering

• Different from seedless plants in that they do not need water for sperm to travel

EQ: How do I describe the function of leaves, stems, roots and flowers?

Three parts to a Seed

• Embryo

• Stored food

• Seed coat

EQ: How do I describe the function of leaves, stems,

roots and flowers?

Embryo

• Young plant that develops from the zygote

• Already has the beginnings of root, stem and leaves

EQ: How do I describe the function of leaves,

stems, roots and flowers?

Cotyledons

• Food stored inside one or two seed leaves

• Embryo uses food stored in seed to help it continue to grow

EQ: How do I describe the function of leaves, stems, roots and flowers?

Seed Coat

• Outer covering of seed

• Acts like plastic wrap and keeps the seed and its food from drying out

• Allows seed to remain dormant for a long time

EQ: How do I describe the

function of leaves, stems, roots and

flowers?

Needs of Seeds

– Light– Water – Nutrients

EQ: How do I describe the function of leaves, stems, roots and flowers?

Seed Dispersal

• Scattering of seeds

• Dispersed many ways– Animals

• digestion• fur or people’s clothing

– Water– Wind– Some plants shoot out their seeds

EQ: How do I describe the function of leaves, stems, roots and flowers?

Germination• Early growth stage of

the embryo

• Steps to germination– Seed absorbs water

from the environment– Embryo uses stored

food to begin to grow– Embryo’s roots grow

down, then leaves and stem grow upward

EQ: How do I describe the function of leaves, stems,

roots and flowers?

Germination

• Seeds which are dispersed far away from the parent have a better chance of survival because it does not have to compete for nutrients, light and water

EQ: How do I describe the function of leaves, stems, roots

and flowers?

Leaves

• Most numerous part to a plant

• Role – capture the sun’s energy and carry out the food making process of photosynthesis

EQ: How do I describe the function of leaves, stems,

roots and flowers?

Leaf Structure

• Bottom and top layers which protect cells

• Leaf veins that contain the xylem and phloem

• Stomata – – underside of leaf has small pores

or openings– Opens and closes to control the

amount of gas that enters and leaves the leaf

EQ: How do I describe the function of leaves, stems, roots

and flowers?

Leaf and Photosynthesis

• Top layer of leaf contains chloroplasts

• Chlorophyll in the chloroplasts trap sun’s energy

EQ: How do I describe the function of leaves, stems,

roots and flowers?

Leaf and Photosynthesis

• Carbon Dioxide enters the leaf through the stomata

• Water, which is absorbed by the plants roots, travels up to plant through xylem

• Sugar and oxygen are produced from the CO2 and H2O.

EQ: How do I describe the function of leaves, stems, roots and flowers?

Leaf and Photosynthesis• Oxygen exits leaf

through stomata

• Sugar enters the phloem and then travels throughout the plant

EQ: How do I describe the function

of leaves, stems, roots and flowers?

Controlling Water Loss

• Transpiration – process by which water evaporates from a plant’s leaves

• Plants slow down transpiration by closing the stomata

EQ: How do I describe the function of leaves, stems,

roots and flowers?

Stems

• Two important functions– Carries substances

between roots and leaves

– Supports plant so leaves are exposed to the sun

EQ: How do I describe the function of leaves, stems,

roots and flowers?

Structure of a Stem

• Two types of stems– Herbaceous – soft

and flexible– Woody-hard and

rigid

• Both types contain phloem and xylem

EQ: How do I describe the function of leaves, stems, roots

and flowers?

Woody Stems

• Bark - added layer of protection • Heartwood – inner layers for additional support

EQ: How do I

describe the

function of leaves, stems,

roots and flowers?

Layers of a Woody Stem1. Bark

2. Phloem

3. Cambium -cells that produce new phloem and xylem

4. Active xylem

5. Heartwood- inactive xylem

6. Pith – center of stem, stores food and water in young treesEQ: How do I describe the

function of leaves, stems, roots and flowers?

Annual Rings• Represent one year in a

tree’s growth

• Made of xylem– Light rings grow in spring– Dark rings grow in

summer

• Two rings together make one year’s growth

EQ: How do I describe the function of leaves, stems, roots and flowers?

Roots

• Anchor plants

• Absorb water and nutrients

EQ: How do I describe the

function of leaves, stems, roots and

flowers?

Types of Roots• 2 types

– Taproot – long thick root with thin roots branching off – carrot, radish, dandelion, cactus

– Fibrous- several main roots that branch repeatedly – lawn, corn, trees

EQ: How do I describe the function of

leaves, stems, roots and flowers?

Structure of Root

• Root cap – contains dead cells, protects root from injury

• Dividing cells – cause root to lengthen

• Root hairs – grow out of root surface – increases the surface area of the roots

• Cambium

• Vascular tissue in centerEQ: How do I describe the function of

leaves, stems, roots and flowers?

Class Work and Homework

• Fill In – What did I learn– Confused – Say

EQ: How do I describe the function of

leaves, stems, roots and flowers?