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Basic_Botany.ppt

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Basic_Botany.ppt

  1. 1. Basic Botany, Plant Physiology, and Environmental Effects on Plant Growth The University of Tennessee Master Gardener Program Updated January 2002
  2. 2. Objectives  To develop a basic understanding of:  Botany  Plant Physiology  Environmental Factors that affect Plant Growth  To apply this basic understanding to home gardening.
  3. 3. Topics  Plant Parts and Functions  Stems  Leaves  Buds  Roots  Flowers  Fruit  Seed  Plant Development  Photosynthesis  Respiration  Transpiration  Environmental Factors Affecting Plant Growth  Temperature  Light  Water
  4. 4. Plant Parts  Reproductive  Flower Buds  Flower  Fruit  Seeds  Plant parts of sexual reproduction  Vegetative  Roots  Stems  Leaves  Leaf Buds  Often used in asexual reproduction (vegetative)
  5. 5. Principal Parts of a Vascular Plant
  6. 6. Stems  Stems support:  Buds  Flowers  Leaves  Stems transport:  Water  Minerals  Sugars  Nodes  The points where leaves develop along a stem  Regions of high cellular activity  The distance between nodes (internode) is affected by:  Light (etiolation)  Water  Nutrients (N and micros)  Genetics
  7. 7. Nodes and Buds  Many plants develop one or more buds at the nodes (axillary buds)  Axillary buds may grow into lateral branches  When pruning a plant it is very important to make cuts just above axillary buds:  Axillary buds grow  Wound heals quickly  When making cuttings, they should be made just below a node:  Many plants root more easily at nodes, some only at nodes.  Managing light, water, nutrients, and genetics are important to healthy transplant production!
  8. 8. Proper Pruning Cut: Tree
  9. 9. Proper Pruning Cut: Cane
  10. 10. Plant Cuttings
  11. 11. Types of Stems  Shoot  A young stem with leaves present  Twig  A stem less than 1 year old with no leaves present (dormant)  Branch  A stem more than 1 year old, with lateral buds  Trunk  A main stem of a woody plant  Trees generally have a single trunk  Shrubs often have 2 or more trunks  Vines  A long trailing stem that is able to support itself by winding around other plants
  12. 12. Types of Stems and Modifications  Canes  A stem that lives only a year or two  Contain a large amount pith (soft tissue) in the center  Stem modifications  Above-Ground  Crowns  Stolons  Spurs  Below-Ground  Bulbs  Corms  Rhizomes  Tubers  All of these have buds or leaves present  Can you think of examples of these structures?
  13. 13. Above-Ground Stem Modifications Stolons and Crowns Spurs
  14. 14. Below-Ground Stem Development Rhizomes Tubers
  15. 15. Below-Ground Stem Development Corm Bulb
  16. 16. Vascular Tissue: “The Plants Circulatory System”  Xylem  Transports water, nutrients, & minerals from roots to upper portions of the plant  Forms the “wood” of woody plants  Phloem  Conducts sugars from leaves to growing points, fruits, & storage areas  Comprises much of the bark of woody plants  Cambium  Cambium is the meristematic tissue (the site of cell division and growth)  It is located between the xylem and phloem and produces both tissues  Other meristematic tissue is found at the apical bud, where stem elongation takes place
  17. 17. Arrangements of Vascular Tissue  “Dicots”  Vascular tissue form rings  Woody plants  “Monocots”  Vascular tissue arranged in bundles  Grasses, Orchids, Lilies  Lack cambium tissue between xylem and phloem  Stems of dicots tend to grow in diameter, while stems of monocots tend not to increase in diameter  What does knowing about these tissues reveal to you about:  Damage to the bark of a tree?  Grafting?
  18. 18. Diagram of Vascular Tissue
  19. 19. Life Span of a Stem  We often classify stems by how long they live:  Annual  Produce seed and die within 1 year  Biennials  Produce vegetative structures and food storage organs the first year  Reproduction takes place the second year and the plant dies  When stressed, biennials can go through the entire process in 1 year (bolting)  Perennials  Live 3 or more years  Usually produce flowers and seeds every year  Herbaceous Perennial  Shoots which die back to the ground every year  “Biennial Perennials”
  20. 20. Leaves  Leaves:  Are attached to the stem by petioles  Consist of:  Blade  Midrib  Smaller Veins  Function  To manufacture sugars in a process called photosynthesis  Functions  Petiole:  Expands the leaf area and orients the leaf  Blade:  Provides a large area for the efficient absorption of light  Midrib and Veins:  Conducts water, sugar, and other compounds throughout the leaf
  21. 21. Type of Leaves
  22. 22. Outer Leaf Structure  Epidermis  Outer protective layer  Trichomes  Extensions of epidermis that make leaves feel like velvet  Cuticle  Waxy layer (cutin) in some plants that protects plants from:  Dehydration  Penetration by some diseases  Guard Cells  Special epidermal cells that are capable of enlarging and contracting  Stomates  Openings that develop between enlarged guard cells  Usually on the underneath side of the leaf  Regulate the passage of water, oxygen, and carbon dioxide in and out of the leaf
  23. 23. Inner Leaf Structure  Mesophyll  Where photosynthesis occurs  Is comprised of 2 layers  Palisade cells  Parenchyma layer  Palisade Cells  Dense upper layers of the leaf  Parenchyma Layer  Lower spongy area with considerable air space  Chloroplasts  Actual site of photosynthesis  Found in the palisade cells and the parenchyma layer  Some plants vary leaf thickness with environmental conditions  Special Leaves  Bracts  Tendrils  Cotyledons
  24. 24. Structure of a Leaf Blade
  25. 25. Bracts
  26. 26. Tendrils
  27. 27. Cotyledons
  28. 28. Leaf Shape and Plant Identification  Leaves are one of the primary characteristics in plant identification  Veining  “Structure”  Shape  Margins  Arrangement  Leaf Veins  Veins are the continuation of vascular tissue from the stem, through the petiole  Veining Patterns  Parallel  Run parallel with length of the leaf  Are connected by minute, straight veins  Prominent in monocots  Net  Pinnate  Palmate  Prominent in dicots
  29. 29. Types of Leaf Veins
  30. 30. Leaf “Structure”, Shape, and Margins  “Structure”  Simple  Compound  Palmate  Pinnate  Double Pinnate  Shape  Blade  Apex  Base  Margins  Entire  Serrate  Crenate  Dentate  Ciliate  Lacerate  Sinuate  Incised  Lobed  Cleft
  31. 31. Simple and Compound Leaf Types
  32. 32. Leaf Shapes
  33. 33. Common Leaf Shapes  Acuminate: Tapering to a long, narrow point.  Acute: Ending in an acute angle, with a sharp but, not acuminate point.  Obtuse: Tapering to a rounded edge.  Sagittate: Arrowhead-shaped, with two pointed lower lobes.  Truncate: Having a relatively square end.
  34. 34. Leaf Margins
  35. 35. Common Leaf Margins  Entire: A smooth edge with no teeth or notches.  Serrate: Having small, sharp teeth pointed toward the apex.  Dentate: Having teeth ending in an acute angle, pointing outward.  Crenate: Having rounded teeth.  Sinuate: Having a pronounced sinus or wavy margin.  Incised: Margin cut into sharp, deep, irregular teeth or incisions.  Lobed: Incisions extend less than halfway to the midrib.  Cleft: Incisions extend more than halfway to the midrib.
  36. 36. Leaf Arrangement  Leaf arrangement along the stem  Rosulate  Basal leaves form a rosette  Short internodes  Opposite  Two leaves exactly opposite  Alternate  Steps or spiraled  Whorled  Circles of three or more leaves  Uses of Leaves  Food  Humans  Animals  Wild  Livestock  Ornamental  Color  Shape  Soil Amendments
  37. 37. Leaf Arrangement
  38. 38. Leaf Arrangement (cont.)
  39. 39. Buds  Buds are undeveloped shoots from which leaf or flower parts arise  Bud Scales  Small, leathery, modified leaves that cover buds  Bud Scale Scars  Scars formed when the bud scales are removed  Used in plant identification  Types of Buds  Terminal – dominant  Auxin  Lateral or axillary  Adventitious  May originate from internodes, leaves, or callus tissue of stems or roots  Chilling Requirements  Bud Use
  40. 40. Roots  Principal Functions  Obvious  Absorb Water  Nutrient Uptake  Also  Transport water and nutrients to the stem  Anchor / Support  Serve as storage organs  Propagation  Parts or Zones of Growth  Merisematic Zone  Where new cells are formed  Root Cap – protects root tip  Zone of Elongation  Cells increase in size and push root  Zone of Maturation  Cells differentiate  Root hairs form – short-lived, small roots - absorption
  41. 41. Root Structure
  42. 42. Root Systems  Two types of Root Systems  Tap  Develops a main tap root with various amounts of lateral rooting  Fibrous  Develops small roots that spread out in a mat-like growth  Uses  Food  Humans  Fresh  Processed  Animals ?  Medicinal  Dried  Fresh ?
  43. 43. Flowers  Flowers are generally the showiest part of the plant, but they also serve a purpose  Sexual Reproduction  Color and / or  Odor attracts pollinators (insects)  Flowers are least influenced by environmental conditions; therefore they are important in plant identification.
  44. 44. Flower Parts  Sepals  Small, green leaf-like structures at the base of the flower that protect the flower bud  Collectively – Calyx  Petals  Colored and aromatic part  Collectively – Corolla  The number of sepals and / or petals helps identify the family or genera  Dicots generally have multiples of 4 or 5  Monocots generally have multiples of 3  Example  Members of the “Rose” family have 5 petals and sepals.
  45. 45. Reproductive Flower Parts  Female  Pistil (shaped like a bowling pin)  Stigma (top)  Style (middle)  Ovary (bottom)  Placenta  Ovules – develop into seed after pollination  Male  Stamen (flowers often have a cluster of stamens around the pistil)  Anther (pollen sac)  Pollen is produced by the anther  Filament (“stem”) supports the anther
  46. 46. Structure of a Generalized Flower
  47. 47. Types of Flowers  Complete – all four parts  Incomplete – lacks one part  Perfect – contains both function pistils and stamens  Imperfect – lacks a functioning pistil or stamen  Self-pollination  Cross-pollination  Monoecious – both male and female flowers on one plant  Dioecious – contains only male or female flowers on a single plant
  48. 48. Common Flower Inflorescences
  49. 49. Common Flower Inflorescences (cont.)
  50. 50. What Is a Fruit?  Something you eat for desert (not with the entrée)  Botanically, fruit is a ripened ovary  Mature ovules (seeds)  Ovary wall (flesh)  Examples  Tomatoes, cucumber, eggplant, beans  Types of fruit  Simple  Single flower – tomato  Aggregate (compound)  Single flower with many ovaries – strawberry  Multiple  Tight cluster of many flowers – pineapple
  51. 51. Seed Structure  Three Main Parts  Embryo – partially developed plant in a dormant state  Radicle – embryonic stem  Hypocotyl – stem  Cotyledons – seed leaves  Plumule – underdeveloped stem and leaves  Endosperm – food source  Seed Coat – protection from insects, diseases, and germination  Seed Growth  Germination – resumption of seed growth  Moisture  Oxygen  Favorable temperature  Light (sometimes)
  52. 52. Primary Parts of Common Seeds
  53. 53. Seed Germination and Storage  Most seeds require time after maturity before they will germinate.  Others will require:  Stratification  Scarification  Soaking  Time, time, time!  Storage  Seeds are living things!  They “live” longer when maintained in a cool and dry environment.  Keep seed packets air tight (except beans ?)  Store in a refrigerator or freezer
  54. 54. Plant Growth and Development  Three major processes  Photosynthesis  Respiration  Transpiration
  55. 55. Photosynthesis  Photosynthesis – “to put together with light”  Requirements:  Light  Carbon Dioxide  Water  Suitable Temperature  Process – very complicated, but a simple description  Carbon dioxide and water are combined using solar energy  Simple sugars (glucose is formed and oxygen is give off (in the chloroplasts)  Simple sugars are then converted into more complex sugars and starches; and stored  All green tissue is capable of photosynthesis, but most takes place in the leaves  What limits photosynthesis?
  56. 56. Respiration and Transpiration  Respiration is the “opposite” of photosynthesis  Carbohydrates are broken down and the energy released is used for life processes  As night-time temperatures increase, respiration increases  Transpiration is the process by which plants loose water vapor  90% of the water entering a plant is transpired  Water movement is important in moving nutrients, minerals, sugars, and other compounds; as well as maintaining turgor pressure and evaporative cooling
  57. 57. How a Plant Grows
  58. 58. Photosynthesis vs. Respiration  Photosynthesis  Produces sugars  Stores energy  Releases oxygen  Uses water  Uses carbon dioxide  Occurs in sunlight  Occurs in chloroplast  Respiration  Uses sugars for energy  Release energy  Uses oxygen  Produces water  Produces carbon dioxide  Occurs in dark and light  Occurs in all cells
  59. 59. Environmental Factors  Primary environmental influencing plant growth  Temperature  Light  Water
  60. 60. Temperature  Temperature is the main environmental factor affecting plant growth  Germination  Cool-Season vs. Warm-Season  Hardiness  Cold – Desiccation  Heat  Growth and fruit set  Temperature influences quality!
  61. 61. Temperature and Germination
  62. 62. Light  Three principal characteristics:  Quantity  Intensity or brightness  Phototropism  Quality  Color or wavelengths  Red and blue light are most important  Green is reflected by the plant  Duration  Photoperiod – amount of time a plant is exposed  Short-Day  Flower during long nights  Mums and poinsettia  Day-Neutral  Not influenced by day length  Ever-bearing strawberries  Long-Day  Flower during short nights  Most summer plants
  63. 63. Light Management Not Enough! Too Much!
  64. 64. Water  Water comprises most of all living things!  The plant is no different!  Main component of protoplasm – the living part of the cell  Water Acquisition  Root hairs  Vascular tissue  Stomates  Quality  Low in salts  Temperature  Quantity  Too much  Diseases  Too little  Wilting  Special structures  Leaves
  65. 65. Water Management Too Much! Not Enough!
  66. 66. Questions?

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