Chapter 19 Plants Man: ©G. R. "Dick" Roberts/Natural Sciences Image Library Copyright © McGraw-Hill Education.  All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education.

Plants Have Changed the World Members of kingdom Plantae are nearly everywhere. Plants harness the energy that sustains ecosystems. They also release O2, which consumers use for respiration. Section 19.1 Snow: ©Design Pics/Carson Ganci/Getty Images RF; Prairie: ©Tetra Images/Tetra Images/Corbis RF; Forest: ©Ted Mead/Getty Images RF Figure 19.1

Highlights in the History of Plants The presence or absence of vascular tissue, pollen and seeds, and flowers defines each plant group. Section 19.1 Figure 19.3

Highlights in the History of Plants Bryophytes have no vascular tissue, seeds, or flowers. Mosses are bryophytes. Section 19.1 Figure 19.3

Highlights in the History of Plants The origin of vascular tissue, which transports water and nutrients in the plant, allowed plants to grow taller. Taller plants reach above their neighbors in the struggle for sunlight. Section 19.1 Figure 19.3

Highlights in the History of Plants Vascular tissue consists of phloem and xylem. Phloem transports sugars. Xylem transports water. Section 19.1 Figures 19.3, 19.4 Stem cross section: © Dr. John D. Cunningham/Visuals Unlimited

Highlights in the History of Plants Lignin is a complex polymer that strengthens cell walls in vascular tissue. Section 19.1 Figures 19.3, 19.4 Stem cross section: © Dr. John D. Cunningham/Visuals Unlimited

Highlights in the History of Plants Modifications in vascular tissue led to the evolution of seedless vascular plants, like ferns. Section 19.1 Figure 19.3

Highlights in the History of Plants The origin of seeds—dormant, protected plant embryos with a nutrient supply—was also adaptive. Seeds might travel far from the parent and only germinate when conditions are favorable. Section 19.1 Figure 19.3

Highlights in the History of Plants Gymnosperms are plants with vascular tissue and seeds, such as pine trees. Cone scale Seed Section 19.1 Figures 19.3, 19.4 Pine cones: © Westend61/Alamy RF

Highlights in the History of Plants More recently, the origin of flowers and fruits introduced new reproductive adaptations. Angiosperms are flowering plants. Section 19.1 Figure 19.3

Fertilized flowers develop into fruits that protect and disperse seeds Highlights in the History of Plants More recently, the origin of flowers and fruits introduced new reproductive adaptations. Angiosperms are flowering plants. Seed contains embryo and its food supply Fertilized flowers develop into fruits that protect and disperse seeds Section 19.1 Figures 19.3, 19.4 Pea pods: ©Corbis RF

All Plants Have Similar Life Cycles The plant life cycle is called alternation of generations, in which a multicellular diploid stage alternates with a multicellular haploid stage. Section 19.1 Figure 19.5

All Plants Have Similar Life Cycles A zygote develops by mitotic cell division into a multicellular, diploid sporophyte. Section 19.1 Figure 19.5

All Plants Have Similar Life Cycles The sporophyte produces haploid spores by meiosis. Section 19.1 Figure 19.5

All Plants Have Similar Life Cycles Haploid spores divide by mitosis into a multicellular, haploid gametophyte. Section 19.1 Figure 19.5

All Plants Have Similar Life Cycles The haploid gametophyte produces gametes by mitotic cell division. Section 19.1 Figure 19.5

All Plants Have Similar Life Cycles These sex cells fuse at fertilization, forming a diploid zygote and starting the cycle anew. Section 19.1 Figure 19.5

All Plants Have Similar Life Cycles The sporophyte and gametophyte shown in this generalized plant life cycle are those of a seedless vascular plant. Section 19.1 Figure 19.5

All Plants Have Similar Life Cycles Substituting images in the alternation of generations produces diagrams of other plant life cycles. Section 19.1 Figure 19.21

Bryophytes Are the Simplest Plants Section 19.2 Figure 19.3

Bryophytes Are the Simplest Plants Bryophytes are seedless plants that lack vascular tissue. They also lack true leaves and roots. Section 19.2 Figure 19.7 Liverwort: ©Edward S. Ross; Hornwort: ©William E. Ferguson; Moss: ©Steven P. Lynch/The Mcgraw-Hill Companies

Bryophytes Are the Simplest Plants Materials move from cell to cell within the plant by diffusion and osmosis. Section 19.2 Figure 19.7 Liverwort: ©Edward S. Ross; Hornwort: ©William E. Ferguson; Moss: ©Steven P. Lynch/The Mcgraw-Hill Companies

Bryophytes Are the Simplest Plants Examples of bryophytes include: Liverworts Hornworts Mosses Section 19.2 Figure 19.7 Liverwort: ©Edward S. Ross; Hornwort: ©William E. Ferguson; Moss: ©Steven P. Lynch/The McGraw-Hill Companies

Bryophytes Are the Simplest Plants The bryophyte life cycle is an alternation of generations. Section 19.2

Bryophytes Are the Simplest Plants Bryophyte life cycle overview Section 19.2 Figure 19.9 Bryophytes: ©Ed Reschke

Moss Life Cycle Figure 29.8 The life cycle of a moss Raindrop Sperm “Bud” Antheridia Male gametophyte (n) Key Haploid (n) Protonemata (n) Diploid (2n) “Bud” Egg Spores Gametophore Archegonia Spore dispersal Female gametophyte (n) Rhizoid Peristome Sporangium FERTILIZATION Figure 29.8 The life cycle of a moss MEIOSIS (within archegonium) Seta Zygote (2n) Capsule (sporangium) Mature sporophytes Foot Embryo Archegonium Young sporophyte (2n) 2 mm Capsule with peristome (SEM) Female gametophytes

Seedless Vascular Plants Section 19.3 Figure 19.3

Seedless Vascular Plants Examples of seedless vascular plants include: Lycopods (not shown) Whisk ferns True ferns Horsetails Seedless vascular plants have xylem and phloem but not seeds. These plants typically have true roots, stems, and leaves. Section 19.3 Figure 19.10 Whisk fern: ©W. Ormerod/Visuals Unlimited; Horsetail: ©Ed Reschke; Beech fern: ©Rod Planck/Science Source

Seedless Vascular Plants The seedless vascular plant life cycle is an alternation of generations. Section 19.3

Seedless Vascular Plants Seedless vascular plant life cycle overview Section 19.3 Figure 19.11 Spores: ©Ed Reschke/Peter Arnold/Getty Images; Fern gametophyte: ©Les Hickok and Thomas Warne, C-Fern

Fern Life Cycle Key Haploid (n) Diploid (2n) Spore (n) Antheridium Young gametophyte Spore dispersal MEIOSIS Sporangium Mature gametophyte (n) Sperm Archegonium Egg Mature sporophyte (2n) Sporangium New sporophyte Zygote (2n) FERTILIZATION Sorus Figure 29.13 The life cycle of a fern Gametophyte Fiddlehead

Gymnosperms Are “Naked Seed” Plants Section 19.4 Figure 19.3

Gymnosperms Are “Naked Seed” Plants The sporophytes of most gymnosperms are woody trees or shrubs. Reproductive structures and leaf types are diverse. Cycad tree: ©Alena Brozova/Alamy; cycad seed: ©Pat Pendarvis; ginko tree: ©Light of Peace/Flickr/Getty Images RF; ginko seed: ©G. R. "Dick" Roberts/Natural Sciences Image Library; conifer tree: ©Jack Dykinga/Nature Picture Library; pine cone: ©Ed Reschke/Peter Arnold/Getty Images; ephedra: ©Gerald & Buff Corsi/Visuals Unlimited; ephedra reproductive structures: ©Edward S. Ross Section 19.4 Figure 19.12

Gymnosperms Are “Naked Seed” Plants Gymnosperms are divided into four groups: Ginkgo Cycads Conifers Gnetophytes Cycad tree: ©Alena Brozova/Alamy; cycad seed: ©Pat Pendarvis; ginko tree: ©Light of Peace/Flickr/Getty Images RF; ginko seed: ©G. R. "Dick" Roberts/Natural Sciences Image Library; conifer tree: ©Jack Dykinga/Nature Picture Library; pine cone: ©Ed Reschke/Peter Arnold/Getty Images; ephedra: ©Gerald & Buff Corsi/Visuals Unlimited; ephedra reproductive structures: ©Edward S. Ross Section 19.4 Figure 19.12

Gymnosperms Are “Naked Seed” Plants Gymnosperm life cycle is an alternation of generations. Section 19.4

Gymnosperms Are “Naked Seed” Plants Gymnosperm life cycle overview Section 19.4 Figure 19.13

Pine Life Cycle Key Haploid (n) Ovule Diploid (2n) Ovulate cone Megasporocyte (2n) Integument Pollen cone Microsporocytes (2n) Mature sporophyte (2n) Megasporangium (2n) Pollen grain Pollen grains (n) MEIOSIS MEIOSIS Microsporangia Microsporangium (2n) Surviving megaspore (n) Seedling Archegonium Figure 30.6 The life cycle of a pine Seeds Female gametophyte Food reserves (n) Sperm nucleus (n) Seed coat (2n) Pollen tube Embryo (2n) FERTILIZATION Egg nucleus (n)

Angiosperms Produce Seeds in Fruits Section 19.5 Figure 19.3

Angiosperms Produce Seeds in Fruits Today, most plant species have reproductive structures called flowers, which develop into seed-toting fruits. Section 19.5 Red maple flower: ©Dwight Kuhn; cattails: ©Hans Reinhard/Okapia/Science Source; bee: ©McGraw-Hill Education; banana flower: ©Igor Prahin/Flickr Open/Getty Images RF Figure 19.16

Angiosperms Produce Seeds in Fruits Flowers produce pollen and eggs; wind or animals usually carry pollen from plant to plant. Fruits protect the seeds and disperse them to new habitats. Section 19.5 Red maple flower: ©Dwight Kuhn; cattails: ©Hans Reinhard/Okapia/Science Source; bee: ©McGraw-Hill Education; banana flower: ©Igor Prahin/Flickr Open/Getty Images RF Figure 19.16

Angiosperms Produce Seeds in Fruits Variation in flowers and fruits is the result of millions of years of evolution. Section 19.5 Red maple flower: ©Dwight Kuhn; cattails: ©Hans Reinhard/Okapia/Science Source; bee: ©McGraw-Hill Education; banana flower: ©Igor Prahin/Flickr Open/Getty Images RF Figure 19.16

Flowers The flower is an angiosperm structure specialized for sexual reproduction Many species are pollinated by insects or animals, while some species are wind-pollinated A flower is a specialized shoot with up to four types of modified leaves: Sepals, which enclose the flower Petals, which are brightly colored and attract pollinators Stamens, which produce pollen on their terminal anthers Carpels, which produce ovules

Stigma Carpel Stamen Anther Style Filament Ovary Petal Sepal Ovule Figure 30.7 The structure of an idealized flower Petal Sepal Ovule

Angiosperms Produce Seeds in Fruits Scientists classify the diverse angiosperms into several taxa, notably the eudicots and monocots. Section 19.5 Figure 19.14

Angiosperms Produce Seeds in Fruits The angiosperm life cycle is an alternation of generations. Section 19.5

Angiosperms Produce Seeds in Fruits Angiosperm life cycle overview Section 19.5 Figure 19.15

Angiosperm Life Cycle Key Haploid (n) Diploid (2n) Microsporangium Fig. 30-10-4 Angiosperm Life Cycle Key Haploid (n) Diploid (2n) Microsporangium Anther Mature flower on sporophyte plant (2n) Microsporocytes (2n) MEIOSIS Generative cell Microspore (n) Ovule (2n) Tube cell Male gametophyte (in pollen grain) (n) Ovary Pollen grains MEIOSIS Germinating seed Stigma Megasporangium (2n) Pollen tube Embryo (2n) Endosperm (3n) Seed coat (2n) Sperm Seed Megaspore (n) Style Antipodal cells Central cell Synergids Egg (n) Figure 30.10 The life cycle of an angiosperm Female gametophyte (embryo sac) Pollen tube Sperm (n) Nucleus of developing endosperm (3n) FERTILIZATION Zygote (2n) Egg nucleus (n) Discharged sperm nuclei (n)

Figure 19.20