Chapter 21 The Plant Kingdom

Chapter 21 2Plants Plants and people Plants, medicines, and bioprospecting The roles of plants in the ecosystem The evolutionary origin of plants Division Rhodophyta—red algae Division Rhodophyta—red algae Division Phaeophyta—brown algae Division Phaeophyta—brown algae Division Chlorophyta—green algae and the origin of land plants Division Chlorophyta—green algae and the origin of land plants

Chapter 21 3Haploid Diploid Gametophytes form by meiosis Spores form by meiosis n nn Alternation of Generations in Plants Spore Mother Cell Egg Sperm Gametes meet & fuse to form zygote Zygote Embryo Sporo- phyte 2 n Spores n Gameto- phyte 2 n n n 2n2n2n2n 2n2n2n2n 2n2n2n2n

Chapter 21 4 The Evolution of Land Plants Roots and rootlike structures Vascular tissue for transport of water & nutrients Stiffening substance (lignin) for support Waxy covering (cuticle) limits evaporation Stomatal pores Mediate gas exchange Mediate gas exchange Regulate water vapor loss Regulate water vapor loss Evolutionary adaptations in plant reproduction Early algae relied on water currents for fertilization Early algae relied on water currents for fertilization Dry land adaptation include the generation of pollen, seeds, flowers, and fruit Dry land adaptation include the generation of pollen, seeds, flowers, and fruit Adaptations in the alternation of generations Adaptations in the alternation of generations

Chapter 21 5 Evolutionary Tree of Major Plant Groups Ancestral Algae Liver- worts MossesBryophytes True vascular tissue & lignin appear Ferns Gymno- sperms Seeds and pollen appear Flowers & Fruits appear Seed Plants Angio- spermsTracheophytes

Chapter 21 6 The Bryophytes Nonvascular plants No true roots, leaves, and stems Still require a moist environment Anchoring rhizoids absorb water & nutrients Reproductive structures protect gametes Still depend on water for fertilization Dominant gametophyte generation

Chapter 21 7 Life Cycle of a Moss (a) Zygote develops into sporophyte within gametophyte Sporophyte Capsule Fertilization M e i o s i s Haploid spores liberated from sporophyte capsule Old Gametophyte Spores disperse and germinate Haploid 1 n Diploid 2 n

Chapter 21 8 Life Cycle of a Moss (b) Haploid 1 n Diploid 2 n Spore germinates into gametophyte Leafy Gametophyte Archegonium produces egg Antheridium produces sperm Sperm swim to egg Fertilization

Chapter 21 9 Liverworts & Mosses Liverworts Female Gametophyte Archegonium (a) (b) Mosses Female Gametophytes Sporophytes

Chapter Division Tracheophyta: Vascular Plants Adapted to life in drier conditions Had to generate body support Had to generate body support Vessels to conduct water and nutrients Vessels to conduct water and nutrients A stiffening substance called lignin A stiffening substance called lignin Seedless plants: club mosses, horsetails, and ferns Sporophyte generation more dominant Sporophyte generation more dominant Fertilization still relies on water Fertilization still relies on water

Chapter Life Cycle of Ferns (a) Haploid 1 n Diploid 2 n Gametophyte Sporophyte develops from gametophyte Root Stem Sporophyte Masses of Sporangia M e i o s i s Haploid spores liberated from sporangium Sporangium

Chapter Life Cycle of Ferns (b) Haploid 1 n Diploid 2 n Haploid spores liberated from sporangium Spores disperse & germinate Gametophyte Archegonium produces egg Antheridium produces sperm Sperm swim to egg Fertilization

Chapter Seed Plants: General Dominance of the sporophyte generation Reproductive adaptations Pollen Pollen – Wind and pollinators for fertilization – Water not required for fertilization Seeds Seeds – Stores food for embryo – Embryo protection for unfavorable environments

Chapter 21 14Seeds (a) Gymnosperm (d) Water Dispersal (c) Wind Dispersal Stored Food Embryo Seed Coat (b) Angiosperm

Chapter Seed Plants: Gymnosperms Nonflowering seed plants Produce "naked seeds" Three divisions: Coniferophyta Coniferophyta Cycadophyta Cycadophyta Ginkgophyta Ginkgophyta Conifers are adapted to dry, cold conditions Thin, waterproof needles to decrease evaporation Thin, waterproof needles to decrease evaporation Evergreen; year-round photosynthesis Evergreen; year-round photosynthesis Produce an "antifreeze" substance in sap Produce an "antifreeze" substance in sap

Chapter Two Uncommon Gymnosperms (a) Gingko (b) A Cycad

Chapter Life Cycle of the Pine (a) Haploid 1 n Diploid 2 n Mature Sporophyte Seedlings (Sporophyte) Male Cone Male Scale M E I O S I S Male gametophytes (pollen) liberated Female Cone Female Scale Ovule Spore-forming Cell M E I O S I S

Chapter Life Cycle of the Pine (b) Haploid 1 n Diploid 2 n MEIOSIS Pollen liberated; Dispersed by wind MEIOSIS Seedlings (Sporophyte) Egg Cell Female Gametophyte Pollen lands on female scale Pollen Tube FERTILIZATION Seed Embryo

Chapter Seed Plants: Angiosperms Flowering seed plants The dominant plant form on Earth Major evolutionary adaptations Flowers to attract pollinators Flowers to attract pollinators Fruit to protect seeds and developing embryo Fruit to protect seeds and developing embryo Broad leaves Broad leaves – Increase photosynthesis during the growing season – Shed during periods of cold and drought Class Monocotyledoneae (monocots): grasses, grains, corn Class Dicotyledoneae (dicots): hardwood trees, shrubs, and herbs

Chapter Life Cycle of a Flowering Plant (a) Fruit Seed Food Embryo Seed Coat Seedling Flower Anther M E I O S I S Ovary Ovule Spore-forming Cell Haploid 1 n Diploid 2 n

Chapter Life Cycle of a Flowering Plant (b) Fruit MEIOSIS MEIOSIS Spore Female Gametophyte Egg Cell Pollen (male gametophyte) Stigma Pollen Tube Sperm Nuclei F E R T I L I Z A T I O N Haploid 1 n Diploid 2 n

Chapter 21 The End