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  • 1. Chapter 3: Plants
  • 2. SummaryWhy are plants important?Evolution4 major groupsLife cycle – generalKey lineages
  • 3. Why are Plants Important?3 categories:  Ecosystem services  Fuels and fibers  Other
  • 4. EvolutionIt started with green algae, confined to a watery environment, ~ 570 mya.Land plants 1st appeared about 450 mya, preceding land animals.
  • 5. EvolutionInvasion of land presented some of the same problems for plants as it did for animals:
  • 6. 4 Major GroupsBased on similar characteristics and order of evolution.  Non-vascular land plants, mosses, liverworts and hornworts  Vascular plants  Seedless vascular plants, club mosses, ferns and horsetails  Gymnosperms have “naked” seeds that protect embryo, conifers, cycads and ginkgos.  Angiosperms have enclosed seeds (fruits) and flowers.
  • 7. Life CycleAlternates between sporophyte (2n) and gametophyte (n) generations.In early land plants the gametophyte stage predominates, later the sporophyte stage dominates.
  • 8. Nonvascular Plants (Bryophytes)Characteristics  Gametophytes are photosynthetic, sporophytes are attached to gametophytes and depend on them for nutrition.  Require water to reproduce  Most are small and live in moist, temperate environments.
  • 9. Non Vascular PlantsPhylum Hepaticophyta – liverworts
  • 10. Nonvascular plantsPhylum Anthocerophyta Phaeocerus leavis – hornworts  Gas Exchange: Stomata (the rest of the plant kingdom has stomata).  Tiny “broom handles” extending from rhizoids (above ground anchors to substrate).
  • 11. Nonvascular PlantsPhylum Bryophyta – mosses *source of peat  Rhizoid = anchor, supports “leaves” which are 1 cell thick.
  • 12. Vascular PlantsMajor developments  Vascular tissues to…  Vessels – vascular tissue modified to provide structure in later species.  2 groups: seedless and seed bearing
  • 13. Seedless Vascular plantsCharacteristics  Primitive vascular tissue.  Roots  *Still dependent on water for transport of sperm to egg.
  • 14. Seedless Vascular PlantsPhylum Lycophyta – club mosses  Extinct varieties were tree- like but surviving species are small.  Major source of coal.
  • 15. Seedless Vascular PlantsPhylum Psilotophyta  Whisk ferns: no leaves or roots, grow on rhizoids or they are epiphytes.  Horsetails: photosynthetic stems, leaves are less prominent than stems in some varieties. Grow well in wet, boggy areas.
  • 16. Seedless Vascular PlantsPhylum Pteridophyta - ferns  Most abundant, closest relative to seed plants. Fern sporangia
  • 17. Seed-bearing Vascular Plants Ch 28Characteristics  Sporophyte stage dominates.  Major development is the seed that protects embryo and allows for a dormant period.  2 types of gametophytes or structures:  Male (pollen-sperm) and  Female (ovary – eggs)
  • 18. Seed-bearing Vascular Plants2 groups  Gymnosperms – “naked” seeds. Ovules (eggs) are partially exposed on scales; sperm are motile or nonmotile.  Angiosperms – “vessel” seeds (fruit). Ovules are totally enclosed, sperm are motile.
  • 19. Seed-bearing Vascular PlantsGymnosperms – 4 phyla  Gnetophyta –  Cycadophyta (cycads) –  Ginkgophyta –
  • 20. Cycad Ginkgo
  • 21. Seed-bearing Vascular PlantsGymnosperms – 4 phyla cont’d  Coniferophyta (conifers) – largest group; pines, firs, cedars, yews, cypresses, etc.  Produce male and female cones.  Pollen grains and ovules develop at the base of scales. Pollen grains float into female cones and stick on ovules.  Female cones take 1-2 seasons to mature and release their seeds.
  • 22. Seed-bearing Vascular PlantsAnthophyta (Angiosperms) – Characteristics  Flowers and fruits  Dominate the plant world
  • 23. Seed-bearing Vascular PlantsAnthophyta – 6 clades.  Basal angiosperms: Amborella, water lilies, star anise.  Core angiosperms:  Magnoliids – magnolias, laurels, etc.  Monocots – derived from Magnoliids, 1 cotyledon (seed leaf), no woody tissue, leaf veins parallel, flower parts are multiples of 3. Lilies, grasses, yucca, irises  Eudicots (true dicots) – 2 cotyledons, leaf veins are web-like, woody tissue, flower parts are multiples of 4-5. Trees, shrubs, annuals.
  • 24. Figure 30-23 30-23a Angiosperms – what is the purpose of flowers? “Corpse” flowers smell like rotting flesh and attract carrion flies.