Plants (Kingdom Plantae)

1. Plants (Kingdom Plantae) • Multicellular eukaryotes • Photoautotrophs • Terrestrial? • Not all plants are terrestrial • Return to water from land • Move to land was a major step

2. Move to Land Required Significant Adaptations • Water uptake and loss • Gas exchange • Reproduction • Support

3. Move to Land • Plants probably evolved from a group of green algae called the charophytes • Are a fringe species exhibiting multicellular traits • Why a fringe species?

5. Features Common to Green Algae and Plants • Chlorophyll a and other accessory pigments (Chl b, b-carotene) • thylakoid membranes stacked into grana

7. Features Common to Green Algae and Plants • Chlorophyll a and other accessory pigments (Chl b, b-carotene) • similar photosynthesizing organelles • cell walls of cellulose • store carbohydrates as starch • alternation of generation

8. Highlights of Plant Evolution • Four major periods • Move onto land (~425 - 475 mya) • prevent desiccation of whole plant • protect reproductive structures • Features seen in mosses (bryophytes)

12. Highlights of Plant Evolution • Evolution of vascular tissue and diversification (~400 mya) • simple diffusion not an option • Mosses - water-conducting tubes • transport and support • larger body size These are features first seen in ferns, horsetail, whisk ferns ****Similar protection of gametes

15. Whisk Fern Horsetail

16. Highlights of Plant Evolution • Evolution of seed (~360 mya) • additional protection from desiccation and predation • dispersal

18. Highlights of Plant Evolution • Emergence of flowering plants (~130 mya) • Seeds in protective ovary • Expanded potential for diversity • Complex structure with great potential for adaptation • Greater sexual reproductive success • Coevolution between insects and angiosperms

21. Nontracheophytes • Mosses, liverworts and hornworts • Probably closest to ancestral form • protected gametangia • lack vascular tissue • Encrusting • Water needed for fertilization

22. Gametophyte Sporophyte Sporophyte relies on gametophyte for nutrients

25. Nonseed Tracheophytes Plants • Ferns, horsetail, club mosses • Retain some traits of mosses • Evolved some traits also seen in seed-producing vascular plants

26. Traits Shared with Nontracheophytes • Antheridia and archegonia retain similar structure • Require water/moisture for sexual reproduction • Production of spores

27. Traits Shared with Seed-Producing Plants • Vascular tissue - greater body size • Sporophyte is dominant stage of life cycle

28. Sporophyte Gametophyte

33. Seedless tracheophytes were the dominant vascular plants for ~ 50 million years • Continents in tropical/subtropical zone • As continents drifted away from equator, conditions changed • Seed-producing plants were present during height of seedless vascular plant success

34. Rise of Seed-Producing Tracheophytes • Well suited for environmental changes • Gametophyte smaller and retained in moist tissues of sporophyte • Pollination rather than swimming sperm • Evolution of seed • gymnosperms and angiosperms

35. Gymnosperm • “naked seed” • still have a seed coat • four divisions • Coniferophyta best known • evergreens • needle-shaped leaves, thick cuticle

37. Sporophyte Gametophyte Gametophyte passes within sporophyte

38. Angiosperms • “protected seed” • most diverse group • 235,000 known species vs. 721 species of gymnosperms • One division - Anthophyta • Two classes • Monocotyledones • Dicotyledones

39. Angiosperms • successful and effective design • different themes of the same design

41. Sporophyte Gametophyte Gametophyte passes within sporophyte

42. Develops into fruit Develop into seeds