Plant morphology

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Plant morphology

  1. 1. Plant Morphology<br />By <br />Jacob Thomas <br />
  2. 2.
  3. 3. Plants have three basic organs: roots, stems, and leaves<br />Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings<br />
  4. 4. ROOT<br />Root is a non-green, underground, descending portion of the plant axis<br />Develops from radicle<br />
  5. 5.
  6. 6. Characteristics of root<br />Descending part<br />Negatively phototrophic<br />Non-green<br />Root cap /root pockets<br />Unicellular root hair<br />No nodes<br />Lateral roots Endogenously<br />
  7. 7. Regions of typical root<br />Root cap – mucigel to lubricate<br />Zone of cell division<br />Zone of elongation<br />Zone of root hair or absorption<br />Zone of maturation or differentiation<br />
  8. 8. Functions of root<br />Anchorage<br />Absorption<br />Conduction of water & minerals<br />Transport of nutrients<br />
  9. 9. Types of root system<br />Tap root system <br />Roots develops, usually from the radicle of an embryo of seed is called tap root & the system is called tap root system.<br />2. Fibrous Root System<br />The roots which develop from any other part of the plant except the radicle is called adventitious root and this system is called adventitious or fibrous root system.<br />eg. Monocot plants<br />
  10. 10. Tap root system<br />Fibrous root System<br />
  11. 11. Modifications of root for storage<br />Conical roots<br />eg. Carrot <br />(Daucuscarota)<br />
  12. 12. Modifications of root for storage<br />b) Fusiform roots<br />eg. Radish <br />(Raphanussativus)<br />
  13. 13. Modifications of root for storage<br />c) Napiform roots<br />eg. Beet<br />(Beta vulgaris)<br />
  14. 14. Modifications of root for mechanical support<br />Epiphytic roots<br /><ul><li>clinging roots
  15. 15. Hanging roots -</li></ul> velamen tissue<br /><ul><li>Absorbing roots</li></ul>eg. Orchids<br />
  16. 16. Modifications of root for mechanical support<br />Stilt roots<br />eg. <br />Maize, <br />Jowar, <br />Sugarcane<br />
  17. 17. Modifications of root for Physiological functions<br />Pneumatophores or <br />Breathing roots<br />eg. <br />Avicennia, <br />Rhizophora, <br />Sonneratia<br />
  18. 18. Modifications of root for Physiological functions<br />Parasitic roots / Haustoria / Sucking roots<br />eg. <br />Total parasite – Cuscuta<br />Partial - Loranthus<br />
  19. 19. Stem<br />Stem is the ascending axis of a plant and develops from the plumule and epicotyle of the embryo<br />Node<br />Shoot system <br />Internode<br />
  20. 20. Characteristics of stem<br /><ul><li>Terminal bud for growth
  21. 21. Ascending axis
  22. 22. Developing from plumule & epicotyle
  23. 23. Phototrophic
  24. 24. Nodes & internodes
  25. 25. Branches & leaves exogenous
  26. 26. Multicellular hair
  27. 27. Bears flowers & fruits</li></li></ul><li>BUDS<br />Young underdeveloped shoot consisting of a shoot apex, compressed axis and a number of tender leaves arching over the growing apex<br />
  28. 28. BUDS<br />Vegetative buds<br />Grow to only leafy shoot<br />
  29. 29. BUDS<br />Apical bud<br />Axillary Bud<br />Mixed Buds<br />Produce both vegetative & floral branches<br />Borne at the apex of main branch<br />Occur in theaxis of leaf<br />
  30. 30. Modifications of stem<br />The structural and functional change in the normal form and structure of the stem due to change in normal function of the stem is called modification of the stem<br />
  31. 31. 1. Underground stem Modifications<br />Herbaceous plants to overcome unfavorable season<br />Examples<br />Root stock<br />Rhizome<br /><ul><li>Perennial stem of the plant grows below soil surface.
  32. 32. Fleshy due to storage of food
  33. 33. Nodes, internodes, scaly leaves, axillary buds, & adventitious roots</li></ul>Straggling rhizome<br />
  34. 34. Bulb<br /><ul><li>Stem underground, disc like, small & modified and reduced
  35. 35. Convex / conical , compressed internodes
  36. 36. Nodes bear fleshy scales
  37. 37. Leaves in concentric
  38. 38. Axillary buds
  39. 39. Adventitious roots</li></li></ul><li>Bulb<br />Tunicated bulb<br />(scaly leaves covering fleshy leaves in concentric)<br />Scaly or naked bulb<br />No covering / overlap one another<br />Tulip <br />
  40. 40. Tuber<br />The tuber stores starch as reserve food material<br />
  41. 41. Corm<br /><ul><li>Fleshy underground round stem
  42. 42. Buds at nodes
  43. 43. Adventitious roots
  44. 44. Food storage</li></li></ul><li>2. Sub-aerial modifications<br /><ul><li>Delicate stem unable to stand erect</li></ul>A. Runner<br />Oxalis<br />Oxalis<br />Doob grass<br />
  45. 45. 2. Sub-aerial modifications<br />B. Stolon<br />Fern<br />Nepenthes<br />
  46. 46. 3. Aerial modification<br />A. Tendril<br /><ul><li>weak stem
  47. 47. Requires support
  48. 48. Axillary buds  spring like tendrils
  49. 49. Sensitive to touch
  50. 50. Coil around
  51. 51. Support to climb up
  52. 52. Expose leaves to sunlight</li></ul>Passiflora<br />Apical bud  tendril<br />Cucumber<br />Extra axillary bud<br />Grapes<br />
  53. 53. 3. Aerial modification<br />B. Thorn<br /><ul><li>Xerophytic plants
  54. 54. Vascular connections with stem
  55. 55. Axillary branches  hard sharp pointed thorns
  56. 56. Protects from animals
  57. 57. Reduces transpiration & desiccation</li></ul>Citrus<br />Bougainvillea<br />Duranta<br />
  58. 58. 3. Aerial modification<br />C. Phylloclade<br /><ul><li>Xerophytic plants
  59. 59. Leaves
  60. 60. stem flat green phylloclade
  61. 61. Check the rate of transpiration</li></ul>Opuntia<br />
  62. 62. 3. Aerial modification<br />D. Cladode<br /><ul><li>Xerophytic plants
  63. 63. Modification of stem & branches of limited growth
  64. 64. Phylloclade with one or two internodes  Cladode</li></ul> Asparagus  needle like, slightly flattened, green, appear in clusters in the axil of a scaly leaf<br />Ruscus looks like leaf. Develops from axil of a scaly leaf. Bearing floral bud<br />Asparagus<br />
  65. 65. 3. Aerial modification<br />E. Bulbil<br /><ul><li>Axillary Bud / vegetative bud  large & fleshy due to storage of food</li></ul>Helps in vegetative Reproduction<br />Dioscorea<br />Allium<br />Agave<br />
  66. 66. Functions<br />Primary<br />Secondary<br /><ul><li>Bears & Holds
  67. 67. Conduction
  68. 68. Lateral growth
  69. 69. Flowers
  70. 70. Fruits & seeds
  71. 71. Perennation
  72. 72. Vegetative propagation
  73. 73. Helps in photosynthesis
  74. 74. Check transpiration
  75. 75. Climbing</li></li></ul><li>Leaf Structure <br />A leaf is held away from its stem by a stem-like appendage called a petiole.<br />The base of the petiole is attached to the stem at a node.<br />The blade is the expanded thin structure on either side of the midrib and is usually the largest, most conspicuous part of a leaf <br />
  76. 76. Leaf Parts <br />The cuticle is part of the epidermis<br />It produces a waxy layer called cutin, which protects the leaf from dehydration and disease. <br />On the top and bottom is a layer of thick, tough cells called the epidermis. Its primary function is to protect the other layers of leaf tissue. <br />
  77. 77. Leaf Parts Continued <br />Special epidermal cells called guard cells open and close in response to environmental stimuli, such as changes in weather and light. <br />They regulate the passage of water, oxygen, and carbon dioxide into and out of the leaf through tiny openings called stomata.<br />Located between the upper and lower epidermis is the mesophyll. <br />Located within the mesophyll cells are chloroplasts, where photosynthesis takes place.<br />
  78. 78. BUDS <br /><ul><li>A bud is an undeveloped shoot from which embryonic leaves or flower parts arise
  79. 79. A leaf budiscomposed of a short stem with embryonic leaves
  80. 80. A flower bud is composed of a short stem with embryonic flower parts.
  81. 81. Buds are named for the location they inhabit on the stem surface.
  82. 82. Enlarged buds or parts of buds form the edible portion of some horticultural crops</li>

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