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2. Resources Chapter Presentation Visual Concepts Transparencies Standardized Test Prep

3. Introduction to Plants Chapter 23 Table of Contents Section 1 Adaptations of Plants Section 2 Kinds of Plants Section 3 Plants in Our Lives

4. Section 1 Adaptations of Plants Chapter 23 Objectives • Summarizehow plants are adapted to living on land. • Distinguishnonvascular plants from vascular plants. • Relatethe success of plants on land to seeds and flowers. • Describethe basic structure of a vascular plant sporophyte.

5. Section 1 Adaptations of Plants Chapter 23 Characteristics of Plants Click below to watch the Visual Concept. Visual Concept

6. Section 1 Adaptations of Plants Chapter 23 Establishment of Plants on Land • Plants are the dominant group of organisms on land, based on weight. • Plants probably evolved from multicellular aquatic green algae that could not survive on land. • Before plants could thrive on land, they had to be able to do three things: absorb nutrients from their surroundings, prevent their bodies from drying out, and reproduce without water to transmit sperm.

7. Section 1 Adaptations of Plants Chapter 23 Evolutionary Relationships Between Plants and Green Algae

8. Section 1 Adaptations of Plants Chapter 23 Establishment of Plants on Land, continued Absorbing Nutrients • Aquatic algae and plants take nutrients from the water around them. • On land, most plants take nutrients from the soil with their roots. • Botanists think that fungi may have helped early land plants to get nutrients from Earth’s rocky surface. Symbiotic relationships between fungi and the roots of plants are called mycorrhizae.

9. Section 1 Adaptations of Plants Chapter 23 Establishment of Plants on Land, continued Preventing Water Loss • A watertight covering, which reduces water loss, made it possible for plants to live on land. This covering, called a cuticle, is a waxy layer that covers the nonwoody aboveground parts of most plants. • Pores called stomata permit plants to exchange oxygen and carbon dioxide. • A pair of specialized cells calledguard cellsborder each stoma. Stomata open and close as the guard cells change shape.

10. Section 1 Adaptations of Plants Chapter 23 Stomata and Guard Cells

11. Section 1 Adaptations of Plants Chapter 23 Establishment of Plants on Land, continued Reproducing on Land • In most plants, sperm are enclosed in a structure that keeps them from drying out. • The structures that contain sperm make up pollen. • Pollen permits the sperm of most plants to be carried by wind or animals rather than by water.

12. Section 1 Adaptations of Plants Chapter 23 Requirements of Plants to Survive on Land Click below to watch the Visual Concept. Visual Concept

13. Section 1 Adaptations of Plants Chapter 23 Vascular Tissue, Seeds, and Flowers Advantages of Conducting Tissue • Specialized cells that transport water and other materials within a plant are found in vascular tissues. • The larger, more-complex plants have a vascular system, a system of well-developed vascular tissues that distribute materials more efficiently. • Relatively small plants that have no vascular system are called nonvascular plants. Plants that have a vascular system are called vascular plants.

14. Section 1 Adaptations of Plants Chapter 23 Vascular Tissue

15. Section 1 Adaptations of Plants Chapter 23 Transporting Materials Throughout the Plant Click below to watch the Visual Concept. Visual Concept

16. Section 1 Adaptations of Plants Chapter 23 Vascular Tissue, Seeds, and Flowers, continued Advantages of Seeds • A seed is a structure that contains the embryo of a plant. • An embryo is an early stage in the development of plants and animals. • Most plants living today are seed plants—vascularplants that produce seeds.

17. Section 1 Adaptations of Plants Chapter 23 Vascular Tissue, Seeds, and Flowers, continued Advantages of Seeds • Seeds offer a plant several survival advantages: 1. The seed coat protects the embryo from drying out, injury, and disease. 2. Most kinds of seeds store a supply of nutrients. 3. Seeds disperse the offspring of seed plants. 4. Seeds make it possible for plant embryos to survive through unfavorable periods such as droughts.

18. Section 1 Adaptations of Plants Chapter 23 Structure and Function of Seeds

19. Section 1 Adaptations of Plants Chapter 23 Vascular Tissue, Seeds, and Flowers, continued Advantages of Flowers • The last important adaptation to appear as plants evolved was the flower, a reproductive structure that produces pollen and seeds. • Most plants living today are floweringplants—seed plants that produce flowers. • Flowering plants that are pollinated by animals produce less pollen, and cross-pollination can occur between individuals that live far apart.

20. Section 1 Adaptations of Plants Chapter 23 Plant Life Cycles • Plants have life cycles in which haploid plants that make gametes (gametophytes) alternate with diploid plants that make spores (sporophytes). • A life cycle in which a gametophyte alternates with a sporophyte is called alternation of generations. • Unlike the green algae with alternation of generations, plants have gametophytes and sporophytes that look very different.

21. Section 1 Adaptations of Plants Chapter 23 Life Cycle of Angiosperm

22. Section 1 Adaptations of Plants Chapter 23 Alternation of Generations Click below to watch the Visual Concept. Visual Concept

23. Section 1 Adaptations of Plants Chapter 23 Plant Life Cycles, continued The Vascular-Plant Sporophyte • The sporophytes of vascular plants have a vascular system with two types of vascular tissue. • Relatively soft-walled cells transport organic nutrients in a kind of tissue called phloem. • Hard-walled cells transport water and mineral nutrients in a kind of tissue called xylem.

24. Section 1 Adaptations of Plants Chapter 23 Plant Life Cycles, continued The Vascular-Plant Sporophyte • The part of a plant’s body that grows mostly upward is called the shoot. • In most plants, the part of the body that grows downward is called the root. • Zones of actively dividing plant cells, called meristems, produce plant growth.

25. Section 1 Adaptations of Plants Chapter 23 Structure of a Vascular Plant

26. Section 1 Adaptations of Plants Chapter 23 Meristem Click below to watch the Visual Concept. Visual Concept

27. Section 2 Kinds of Plants Chapter 23 Objectives • Describethe key features of the four major groups of plants. • Classifyplants into one of the 12 phyla of living plants.

28. Section 2 Kinds of Plants Chapter 23 Nonvascular Plants Key Features of Nonvascular Plants • All nonvascular plants are small and relatively simple. • The gametophytes of nonvascular plants are larger and more noticeable than the sporophytes. Hairlike projections called rhizoids anchor the gametophytes to the surfaces on which they grow. • Nonvascular plants must be covered by a film of water in order for fertilization to occur.

29. Section 2 Kinds of Plants Chapter 23 Characteristics of Nonvascular Plants Click below to watch the Visual Concept. Visual Concept

30. Section 2 Kinds of Plants Chapter 23 Nonvascular Plants, continued Kinds of Nonvascular Plants • The mosses (phylum Bryophyta) are the most familiar nonvascular plants. • Like the mosses, liverworts (phylum Hepatophyta) grow in mats of many individuals. Liverworts have no conducting cells, no cuticle, and no stomata. • The hornworts (phylum Anthocerophyta) are a small group of nonvascular plants that, like the liverworts, completely lack conducting cells.

31. Section 2 Kinds of Plants Chapter 23 Types of Nonvascular Plants Click below to watch the Visual Concept. Visual Concept

32. Section 2 Kinds of Plants Chapter 23 Parts of a Moss Click below to watch the Visual Concept. Visual Concept

33. Section 2 Kinds of Plants Chapter 23 Seedless Vascular Plants • Vascular plants that do not produce seeds are called seedless vascular plants. • The earliest known seedless vascular plant, Cooksonia, had sporophytes that had branched, leafless stems that were only a few centimeters long. • Rhynia, another early seedless vascular plant, had horizontal underground stems, or rhizomes.

34. Section 2 Kinds of Plants Chapter 23 Seedless Vascular Plants, continued Key Features of Seedless Vascular Plants • Seedless vascular plants have a vascular system with both xylem and phloem. • The sporophytes of seedless vascular plants are larger than the gametophytes. • The spores of the seedless vascular plants have thickened walls that are resistant to drying.

35. Section 2 Kinds of Plants Chapter 23 Characteristics of Vascular Plants Without Seeds Click below to watch the Visual Concept. Visual Concept

36. Section 2 Kinds of Plants Chapter 23 Seedless Vascular Plants, continued Kinds of Seedless Vascular Plants • The ferns (phylum Pterophyta) are the most common and most familiar seedless vascular plants. • Most fern sporophytes have a rhizome that is anchored by roots and leaves called fronds. • Unlike true mosses, the club mosses (phylum Lycophyta), have roots, stems, and leaves.

37. Section 2 Kinds of Plants Chapter 23 Parts of a Fern Click below to watch the Visual Concept. Visual Concept

38. Section 2 Kinds of Plants Chapter 23 Seedless Vascular Plants, continued Kinds of Seedless Vascular Plants • Some club mosses have clusters of nongreen spore-bearing leaves form a structure called a cone. • The vertical stems of horsetails, which grow from a rhizome, are hollow and have joints. • The whisk ferns (phylum Psilotophyta) probably most closely resemble the earliest vascular plants.

39. Section 2 Kinds of Plants Chapter 23 Needles and Cones Click below to watch the Visual Concept. Visual Concept

40. Section 2 Kinds of Plants Chapter 23 Types of Seedless Vascular Plants Click below to watch the Visual Concept. Visual Concept

41. Section 2 Kinds of Plants Chapter 23 Gymnosperms • Gymnosperms are seed plants whose seeds do not develop within a sealed container (a fruit). • The word gymnosperm comes from the Greek words gymnos, meaning “naked,” and sperma, meaning “seed.”

42. Section 2 Kinds of Plants Chapter 23 Gymnosperms, continued Key Features of Gymnosperms • All gymnosperms produce seeds. • All seed plants produce very tiny gametophytes of two types—male and female. • The sperm of gymnosperms do not swim through water to reach and fertilize eggs. Instead, the sperm are carried to the structures that contain eggs by pollen, which can drift on the wind.

43. Section 2 Kinds of Plants Chapter 23 Characteristics of Gymnosperms Click below to watch the Visual Concept. Visual Concept

44. Section 2 Kinds of Plants Chapter 23 Gymnosperms, continued Kinds of Gymnosperms • The conifers (phylum Coniferophyta) are the most familiar, and most successful, gymnosperms. • The cycads (phylum Cycadophyta) have short stems and palmlike leaves. • The only living species of ginkgo (phylum Ginkgophyta), or maidenhair tree, has fan-shaped leaves that resemble the leaves of the maidenhair fern. • The gnetophytes (phylum Gnetophyta) are a diverse group of trees, shrubs, and vines that produce pollen and seeds in cones that resemble flowers.

45. Section 2 Kinds of Plants Chapter 23 Types of Gymnosperms Click below to watch the Visual Concept. Visual Concept

46. Section 2 Kinds of Plants Chapter 23 Angiosperms • Most seed plants are flowering plants, or angiosperms. • Angiosperms produce seeds that develop enclosed within a specialized structure called a fruit. • The word angiosperm comes from the Greek words angeion, meaning “case,” and sperma, meaning “seed.”

47. Section 2 Kinds of Plants Chapter 23 Angiosperms, continued Key Features of Angiosperms • The male and female gametophytes of angiosperms develop within flowers, which promote pollination and fertilization more efficiently than do cones. • Although fruits provide some protection for developing seeds, their primary function is to promote seed dispersal. • The seeds of angiosperms have a supply of stored food called endosperm at some time during their development.

48. Section 2 Kinds of Plants Chapter 23 Characteristics of Angiosperms Click below to watch the Visual Concept. Visual Concept

49. Section 2 Kinds of Plants Chapter 23 Endosperm Click below to watch the Visual Concept. Visual Concept

50. Section 2 Kinds of Plants Chapter 23 Angiosperms, continued Kinds of Angiosperms • Botanists divide the angiosperms into two subgroups—monocots and dicots. • The monocotsare flowering plants that produce seeds with one seed leaf (cotyledon). • The dicots are flowering plants that produce seeds with two seed leaves.