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Plant Diversity

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Section Outline

What is a Plant? • Multicellular• Eukaryotic• Have cell walls• Carry out photosynthesis using the green pigments

- chlorophyll a, and chlorophyll b

Section 22-2

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What Plants Need to Survive• Sunlight - plants use sunlight to carry out

photosynthesis. Plants display adaptations shaped by the need to gather

• Water and Minerals - all cells need a constant supply of water. Water is a raw material for photosynthesis, so when the sun is shining water gets used up

• Gas Exchange - plants require oxygen for cellular respiration and need carbon dioxide to carry out photosynthesis.

- plants must exchange these gasses with the atmosphere without losing excessive amounts of water from evaporation

Section 22-3

Section Outline

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Early Plants

• For most of Earth’s history, plants did not exist • Life was concentrated in the oceans - algae and

photosynthetic prokaryotes added oxygen to the atmosphere.

• When plants appeared much of the existing life on Earth changed.

• As early plants colonized land, they changed the environment in ways that made it possible for other organisms to develop.

• New ecosystems emerged and organic matter began to form soil

Section 22-3

Section Outline

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Floweringplants

Cone-bearingplants

Ferns andtheir relatives

Mosses andtheir relatives

Green algaeancestor

Flowers; SeedsEnclosed in Fruit

Seeds

Water-Conducting(Vascular) Tissue

Section 22-1

Figure 22–6  A Cladogram of Plant Groups

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Section 22-1

Figure 22-7 The Diversity of Plants

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Bryophytes• Mosses, liverworts, hornworts• Bryophytes lifecycles depend on water for reproduction• Lack vascular tissue - water is drawn up only by osmosis• Mosses are most common, they are most abundant in

areas with water - swamps and bogs, near streams, and in rain forests.

• Mosses are the most abundant plants in the polar region

Section 22-3

Section Outline

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Rhizoid

Capsule

StalkSporophyte

Gametophyte

Stemlikestructure

Leaflikestructure

Section 22-2

The Structure of a Moss

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Evolution of vascular tissue•Xylem - the transport system that carries water up from the roots•Phloem - transports solutions of nutrients and carbohydrates produced by photosynthesis•With the evolution of vascular tissues what challenges could early plants overcome?

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Ferns and their relatives

•Seedless vascular plants•Have true roots, stems, and leaves•Club Mosses, horsetails, and ferns•Ferns reproduce using spores

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Seed Plants• Reproduction free from water• Adaptations that allow plants to reproduce without water

include flowers or cones, the transfer of sperm by pollination, and the protection of embryos in seeds

• Seed plants are divided into two groups.• Gymnosperms - bear their seeds on cones• Angiosperms - flowering plants - bear their seeds in a layer

of tissue to protect the seeds (Fruit)

Section 22-3

Section Outline

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Comparing Features of Seed PlantsComparing Features of Seed Plants

Feature

Seeds

Reproduction

Examples

Feature

Seeds

Reproduction

Examples

Section 22-4

Compare/Contrast Table

Gymnosperms Angiosperms

Bear their seeds on cones

Can reproduce without water; male gametophytes are contained in pollen grains; fertilization occurs by pollination

Conifers, cycads, ginkgoes, gnetophytes

Bear their seeds within flowers

Can reproduce without water; male gametophytes are contained in pollen grains; fertilization occurs by pollination

Grasses, flowering trees and shrubs, wildflowers, cultivated flowers

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Seed coat

Embryo

Storedfood supply

Seed

Wing

A

B

Section 22-4

Figure 22–19 The Structure of a Seed

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22–5 Angiosperms—Flowering PlantsA. Flowers and Fruits

B. Diversity of Angiosperms

1. Monocots and Dicots

2. Woody and Herbaceous Plants

3. Annuals, Biennials, and Perennials

Section 22-5

Section Outline

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are categorized as

that completetheir life cycle in

that completetheir life cycle in

that completetheir life cycle in

Section 22-5

Concept Map

Plants

Annuals Biennials Perennials

1 growingseason 2 years

More than2 years

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Monocots Dicots

Seeds

Leaves

Flowers

Stems

Roots

Single cotyledon

Parallel veins

Floral parts often in multiples of 3

Vascularbundlesscattered throughout stem

Fibrous roots

Two cotyledons

Branched veins

Floral parts often in multiplesof 4 or 5

Vascularbundlesarranged ina ring

Taproot

Section 22-5

Figure 22–25 Comparison ofMonocots and Dicots

Go Online

The latest discoveries in plants

Bryophyte activity

Career links on botanical illustrators

Interactive test

For links on classifying plants, go to www.SciLinks.org and enter the Web Code as follows: cbn-7221.

For links on seedless vascular plants, go to www.SciLinks.org and enter the Web Code as follows: cbn-7223.

For links on seed plants, go to www.SciLinks.org and enter the Web Code as follows: cbn-7224.

Interest Grabber Answers

1. With your partner, list five items you use daily that are byproducts of plants.

Student lists will vary, but should include some of the following items: oxygen, food, fruit, wood, water.

2. With your partner, list three items that plants must get from animals—either directly or indirectly.

Student lists will vary, but should include some of the following items: water, carbon dioxide, nutrients (from decaying animals), soil.

3. Using your answers to questions 1 and 2, construct a diagram that illustrates the interdependence of plants and animals.

Student diagrams should indicate plant–animal interdependence.

Interest Grabber Answers

1. Mosses have leaves that are only one cell thick. What will likely happen to these plants when the air is dry?

Water in their cells will evaporate, and they will dry out.

2. What special features might mosses have to protect them from dry air?

Possible answers: coatings on their leaves to prevent evaporation; ways to store water for their cells.

3. Do you think mosses are better suited to live on riverbanks or on desert slopes? Explain your answer.

Riverbanks; because the leaves of mosses are only one cell thick, they probably dry out easily and so need moist environments, such as riverbanks.

Interest Grabber Answers

List the functions of each of the following parts of a plant:

1. roots

Support the plant; take in water from the soil; anchor plant in soil

2. leaves

Capture sunlight; perform photosynthesis

3. stems

Support the leaves; carry water and food up and down the plant

4. flowers and cones

Reproduction

Interest Grabber Answers

1. In addition to sesame seeds, what are some other seeds that are found in or on top of loaves of bread?

Most students will list poppy seeds and caraway seeds. In addition, some “multi-grain” breads contain millet and flax seeds.

2. In addition to corn, what are some other seeds that are eaten as “vegetables”?

Peas and all types of beans, such as lima beans, black beans, kidney beans, and so on

3. What are some seeds that you have eaten as snack foods?

Sunflower seeds, pumpkin seeds, peanuts

4. What types of nutrients are found in seeds?

Carbohydrates, proteins, and fats

5. Do seeds have the same nutritional value for plants as they do for animals? Explain your answer.

Yes. Plants and animals use the same nutrients to live.

Interest Grabber Answers

1. Memorial Day, President’s Day, and Independence Day are allexamples of annual holidays. Using this information, how often does an annual event occur?

Once every year

2. Bimonthly magazines are published every two months. Biweekly newspapers are published every two weeks. Using this information,how often does a biennial event occur?

Once every two years

3. Distinguish between the life spans of annual plants and biennial plants.

Their life spans differ in the number of years the plants live. Because annual holidays occur once a year, annual plants would likely die after one year. Because biennial events occur once every two years, biennial plants would probably die after two years.