Plant lecture 3 Plants on land and plant structure A Gymnosperms Conifers cycads ginkgos and Gnetophytes i Adaptations Reduction of the gametophyte generation Evolution of pollen Evolution of the seed ii Life cycle B Flowering plants Anthophyta Monocots vs Dicots Plant structure and growth Three 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 alive Growth Meristems Apical growth vs lateral growth Secondary growth via cork cambium and vascular cambium Mechanism of primary growth of in roots and shoots Mechanism of secondary growth in stems Anatomy of a woody tree stem C Plant lecture 4 Plant sex ATypical angiosperm life cycle B Reproductive anatomy i The flower four basic floral organs Stamens Carpels Petals and Sepals ii The anther modified leaves called stamens bear the pollen producing microsporangia iii Pollen variation between species but consistency within a species iv The ovule v Some floral distinctions perfect vs imperfect flowers monoecious vs dioecious species vi 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 Pollination Pollen development Ovule development Pollination Self incompatability Double fertilization D Embryology Endosperm development Embryo development Fruit and seed morphology Seed dormancy Fruit seed dispersal E Asexual reproduction Fragmentation stolons and rhizomes Apomixis F Pollination of flowers by beetles bees moths birds bats and wind John Latto 7 26 07 Plant lecture 5 Water relations and mineral nutrition AWater transport mechanisms i Strasburger s experiment living pumps unlikely leaves play a crucial role and roots are not essential ii Root pressure alone is not sufficient iii Increased solute potential in leaf mesophyll cells creates pull due to Osmotic potential water moves from a less to a more conentrated solution Cohesive forces in water Hydrophilic attraction to cell wall B Stomata actual gap is the stoma surrounded by two guard cells i Stomatal opening controlled by Potassium ions ii 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 CO 2 level abscissic acid and light C Roots root hairs are important in increasing surface area i 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 environments i Adaptations to dry environments Reduced or modified leaves Thick cuticle Crassulacean acid metabolism ii Adaptations to wet environments Pneumatophores iii Adaptations to saline environments saline tolerant plants are known as halophytes Accumulate or excrete sodium E Phloem transport i Bulk flow source to sink caused by pressure differences through sieve tubes ii Source and sink may differ at different times of the year F Nutrition i 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 nodules iv 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 ecology APlant population biology i Indeterminate growth and phenotypic plasticity ii Recruitment and dispersal Seed dispersal by wind gravity Seed dispersal by animals birds ants mammals iii Dormancy and the seedbank iv Recruitment of seedlings v Sedentary with asymmetric competition Self thinning vi Interactions between plants direct and indirect vii Interactions between plants and animals Effects of plants on herbivores generally may be more pronounced than the impact of herbivore feeding on plants BC Plant community ecology i Plant distributions Janzen s pest pressure hypothesis Plant succession revisited the importance of gaps How do plants defend themselves i Attack by microorganisms Barrier redundancy phytoalexins pathogenesis related proteins acetylsalicylic acid ii Attack by herbivores Physical defenses chemical defense and regrowth Chemical defenses secondary products quantitative and qualitative defenses John Latto 7 26 07
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