Plant lecture 3 - Plants on land and plant structurePlant lecture 3 - Plants on land and plant structureA - Gymnosperms: Conifers, cycads, ginkgos and Gnetophytesi) Adaptations: Reduction of the gametophyte generation, Evolution of pollen, Evolution of the seedii) Life cycle B - Flowering plants (Anthophyta)Monocots vs. DicotsC - Plant structure and growthThree tissue types i) Vascular tissue: tracheids, vessel elements and fibers ii) Dermal Tissue iii) Ground Tissue Three cell types i) Parenchyma: general, not thickened, alive ii) Sclerenchyma: thickened, dead iii) Collenchyma: thickened, aliveGrowthMeristems, Apical growth vs.lateral growth, Secondary growth via cork cambium and vascular cambiumMechanism of primary growth of in roots and shoots, Mechanism of secondary growth in stems, Anatomy of a woody tree stemPlant lecture 4 - Plant sexA - Typical angiosperm life cycle B - Reproductive anatomyi) The flower – four basic floral organs: Stamens, Carpels, Petals and Sepalsii) The anther – modified leaves called stamens bear the pollen producing microsporangiaiii) Pollen – variation between species but consistency within a species.iv) The ovulev) Some floral distinctions – perfect vs. imperfect flowers, monoecious vs. dioecious speciesvi) Evolutionary trends: reduction in the number of floral parts, fusion of parts, symmetry goes from radial to bilateral,ovary drops below petals where it is better protected.C - PollinationPollen development, Ovule development, Pollination, Self-incompatability, Double fertilizationD - EmbryologyEndosperm development, Embryo development, Fruit and seed morphology, Seed dormancy,Fruit & seed dispersalE - Asexual reproductionFragmentation: stolons and rhizomes, ApomixisF - Pollination of flowers by: beetles, bees, moths, birds, bats and wind. John Latto 7/26/07Plant lecture 5 - Water relations and mineral nutritionA - Water transport mechanismsi) Strasburger’s experiment – living pumps unlikely, leaves play a crucial role and roots are not essential.ii) Root pressure alone is not sufficientiii) Increased solute potential in leaf mesophyll cells creates ‘pull’ due to:Osmotic potential –water moves from a less to a more conentrated solutionCohesive forces in waterHydrophilic attraction to cell wallB - Stomata – actual gap is the stoma surrounded by two guard cellsi) Stomatal opening controlled by Potassium ionsii) Actively transported into cells which increases their solute concentration. They thus take up water, altering their shape to open the stoma.iii) Potassium uptake controlled by several factors including CO2 level, abscissic acid and light.C - Roots – root hairs are important in increasing surface areai) Water moves in due to a more negative water potential in the root cells.ii) Water may move through the apoplast (in and between cell walls) or the symplast (through cells).iii) Water moving through the apoplast is unregulated (does not pass through selectively permeable cell membranes).iv) The casparian strip (a waxy ‘gasket’) forces water entering the vascular tissue to pass through the symplast.D - Adaptations to harsh environmentsi) Adaptations to dry environments: Reduced or modified leaves, Thick cuticle, Crassulacean acid metabolismii) Adaptations to wet environments: Pneumatophoresiii) Adaptations to saline environments (saline tolerant plants are known as halophytes) Accumulate or excrete sodiumE - Phloem transporti) Bulk flow (source to sink caused by pressure differences) through sieve tubesii) Source and sink may differ at different times of the year.F - Nutritioni) Macronutrients (Carbon, Oxygen, Hydrogen, Nitrogen, Sulfur, Phosphorous, Potassium, Calcium and Magnesium)ii) Micronutrients (Chlorine, Iron, Boron, Manganese, Zinc, Copper, Molybdenum and Nickel)iii) Nitrogen fixation – plants cannot use Nitrogen gas, they use ammonium or nitrate. A few species of bacteria produce nearly all the nitrogen that is used by plants. In some species they are found in root nodulesiv) Deficiency diseases – typically very characteristic of the nutrient that is deficient.v) Parasites and carnivores – alternate solutions to the problem of obtaining nutrients – particularly nitrogen.Plants lecture 6 - Plant ecologyA - Plant population biologyi) Indeterminate growth and phenotypic plasticityii) Recruitment and dispersal: Seed dispersal by wind/gravity, Seed dispersal by animals: birds, ants, mammalsiii) Dormancy and the seedbankiv) Recruitment of seedlingsv) Sedentary with asymmetric competition: Self-thinningvi) Interactions between plants: direct and indirectvii) Interactions between plants and animalsEffects of plants on herbivores (generally) may be more pronounced than the impact of herbivore feeding on plantsB - Plant community ecologyi) Plant distributions: Janzen’s pest pressure hypothesisPlant succession revisited: the importance of gapsC - How do plants defend themselves?i) Attack by microorganisms: Barrier, redundancy, phytoalexins, pathogenesis related proteins, acetylsalicylic acidii) Attack by herbivores Physical defenses, chemical defense and regrowth. Chemical defenses: secondary products – quantitative and qualitative defenses John Latto
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