The document summarizes key aspects of the plant kingdom, including their multicellular nature, ability to photosynthesize, and alternation of generations between haploid and diploid forms. It describes the evolution of plants from green algae ancestors and their adaptations to life on land, including roots, vascular tissue, and waxy cuticles. Seed plants evolved pollen, seeds, and fruits to reproduce on land without water, while angiosperms further developed flowers, broad leaves, and fruits to disperse seeds. Plants play a crucial ecological role by producing oxygen and decomposing to form soil.

1. The Plant Kingdom

2. Key Features of Plants Multicellularity Ability to photosynthesize (most) Exhibit alternation of generations (a multicellular diploid generation alternates with a multicellular haploid generation)

3. Alternation of Generations Diploid sporophyte plant produces haploid spores through meiosis Spores divide by mitosis and develop into haploid gametophyte plants Haploid gametophyte plant produces haploid gametes through mitosis Gametes fuse to form diploid zygotes , which divide by mitosis and develop into diploid sporophytes

4. Alternation of Generations in Plants Gametophytes form by meiosis Spores form by meiosis n n n 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 2 n 2 n 2 n Haploid Diploid

5. Evolution of Plants The evolutionary origin of plants Division Rhodophyta—red algae Division Phaeophyta—brown algae Division Chlorophyta—green algae and the origin of land plants

6. Green Algae Several lines of evidence support the hypothesis that green algae gave rise to plants DNA comparisons show that green algae are plants’ closest living relatives Both use the same type of chlorophyll and accessory pigments in photosynthesis Both store food as starch Both have cell walls made of cellulose

7. Fresh Water Ancestors Most green algae live in fresh water, suggesting that early plants evolved in freshwater habitats Early green algae must have evolved characteristics to withstand the challenges of fresh water habitats, e.g. temperature extremes, periods of dryness These adaptations provided a foundation for descendants to evolve traits for life on land

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

9. Reproduction Without Water Pollen A reduced male gametophyte that allows wind (instead of water) to carry sperm to eggs Seeds Nourish, protect, and help disperse developing embryos Flowers Attract pollinators Fruits Attract animals to disperse seeds

10. Major Groups of Plants Bryophytes ( nonvascular plants ) Lack well-developed structures for conducting water and nutrients Tracheophytes ( Vascular plants ) Have a complex vascular system

11. Evolutionary Tree of Major Plant Groups Ancestral Algae Liver- worts Mosses True vascular tissue & lignin appear Ferns Gymno- sperms Seeds and pollen appear Flowers & Fruits appear Angio- sperms Bryophytes Seed Plants Tracheophytes

12. 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

13. Liverworts & Mosses Liverworts Female Gametophyte Archegonium (a) Mosses Female Gametophytes Sporophytes (b)

14. The Bryophytes: Reproduction Gametes develop within protected structures on gametophyte Archegonia (singular, archegonium) produce eggs Antheridia (singular, antheridium) produce sperm Archegonia and antheridia may be located on the same plant or on different plants

15. Life Cycle of a Moss (a) Zygote develops into sporophyte within gametophyte Sporophyte Capsule Fertilization Meiosis Haploid spores liberated from sporophyte capsule Old Gametophyte Spores disperse and germinate Haploid 1 n Diploid 2 n

16. 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

17. The Vascular Plants Have roots, stems, and leaves Have vessels impregnated with the stiffening agent lignin Sporophyte generation is dominant Include the seedless vascular plants and the seed plants

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

19. Life Cycle of Ferns (a) Haploid 1 n Diploid 2 n Gametophyte Sporophyte develops from gametophyte Root Stem Sporophyte Masses of Sporangia Meiosis Haploid spores liberated from sporangium Sporangium

20. 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

21. Seedless Plants Club Mosses Horsetails Ferns

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

23. Seeds (a) Gymnosperm (d) Water Dispersal (c) Wind Dispersal Stored Food Embryo Seed Coat (b) Angiosperm

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

25. Two Uncommon Gymnosperms (a) Gingko (b) A Cycad – either male or female

26. Gymnosperms: Conifers Adapted to dry, cold conditions: Retain green leaves throughout the year (evergreen) Thin, needle-like leaves covered with waterproofing material to reduce evaporation Produce an “antifreeze” in sap

27. Life Cycle of the Pine (a) Haploid 1 n Diploid 2 n Mature Sporophyte Seedlings (Sporophyte) Male Cone Male Scale MEIOSIS Male gametophytes (pollen) liberated Female Cone Female Scale Ovule Spore-forming Cell MEIOSIS

28. 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

29. Seed Plants: Angiosperms Flowering seed plants The dominant plant form on Earth Major evolutionary adaptations Flowers to attract pollinators Fruit to protect seeds and developing embryo Broad leaves Increase photosynthesis during the growing season Shed during periods of cold and drought

30. Monocot vs Dicot Class Monocotyledoneae (monocots): grasses, grains, corn 1 cotyledon leave veins in parallel lines Flower parts, in multiple of 3 scattered vascular bundles Class Dicotyledoneae (dicots): hardwood trees, shrubs, and herbs 2 cotyledons, web-like veins, flower petals in 4/5s, ringed vascular bundles

32. Flowers Flowers are reproductive structures in which both male and female gametophytes are formed Believed to have evolved when gymnosperm ancestors formed an association with animals Animals benefited by eating some of the protein-rich pollen Plants benefited by using animals as pollinators Most flowers are showy and attract animal pollinators (e.g. insects)

33. Life Cycle of a Flowering Plant (a) Fruit Seed Food Embryo Seed Coat Seedling Flower Anther MEIOSIS Ovary Ovule Spore-forming Cell Haploid 1 n Diploid 2 n

34. Life Cycle of a Flowering Plant (b) Fruit MEIOSIS MEIOSIS Spore Female Gametophyte Egg Cell Pollen (male gametophyte) Stigma Pollen Tube Sperm Nuclei FERTILIZATION Haploid 1 n Diploid 2 n

35. Fruits Encourage Seed Dispersal Fruits are mature ovaries that contain developing seeds Various fruit adaptations help disperse seeds Edible fruits entice animals to eat them (seeds pass through digestive tract unharmed) Burrs cling to animal fur Winged fruits are carried through the air

36. Broad Leaves Broad leaves of angiosperms collect more sunlight for photosynthesis than narrow leaves of gymnosperms Temperate angiosperms drop leaves to conserve water when it is in short supply (fall, winter) Tropical and subtropical angiosperms are evergreen May shed leaves during dry season

37. Broad Leaves Photosynthetic advantage is offset by fact that broad, tender leaves are more appealing to herbivores than tough, waxy needles of conifers Angiosperm defenses include Physical defenses (thorns, spines, resins) Chemical defenses (make plant tissue poisonous or distasteful)

38. Crucial Ecological Role Through photosynthesis, plants provide food, directly or indirectly, for all of the animals, fungi, and non-photosynthetic microbes on land Plants produce oxygen gas as a byproduct of photosynthesis, continually replenishing oxygen in the atmosphere

39. Crucial Ecological Role Plants help create and maintain soil Dead plant material is decomposed by fungi, prokaryotes, and other decomposers Decomposed plant tissue becomes part of the soil, making it more fertile Roots of living plants help hold soil together, preventing erosion by wind and water

40. Human Necessities and Luxuries Plants provide shelter Wood is used to construct housing Plants provide fuel Wood: important fuel for warming and cooking in many parts of the world Coal: derived from the remains of ancient plants that have been transformed by geological processes

41. Human Necessities and Luxuries Plants provide medicine Many medicines and drugs were originally found in and extracted from plants, e.g. aspirin, Taxol, morphine Plants provide pleasure Flowers, gardens, and lawns Coffee, tea, and wine

42. The End