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  1. 1. Leaves By : Geonyzl Lepiten
  2. 2. Leaf <ul><li>Leaves provide trees with all their food because they turn sunlight into food energy. </li></ul>
  3. 3. There are three main parts to a leaf: <ul><li>The base which is the point at which the leaf is joined to the stem. The stalk or petiole is the thin section joining the base to the lamina - it is generally cylindrical or semicircular in form. The lamina or leaf blade is the wide part of the leaf </li></ul>http://www.butler.edu/herbarium/treeid/treeparts.html
  4. 4. Compound leaf
  5. 5. Primary division of leaves ( types of leaf configuration ) Simple Compound http://www.butler.edu/herbarium/treeid/treeparts.html
  6. 6. <ul><li>The leaf  blade has two types of configuration . It may be in one unit , in which case the leaf is called a simple leaf , or it may be divided into numerous small parts that look like individual leaves and which form a compound leaf . It may be difficult to tell whether one is looking at a simple leaf or the leaflet (pinna) of a compound leaf.  The distinction can be made by the fact that a leaf (simple or compound) has an axial bud between the petiole and the stem . </li></ul>
  7. 7. Types of simple leaves <ul><li>Are classified base on the following: </li></ul><ul><li>1. leaf margin </li></ul><ul><li>2. venation </li></ul><ul><li>3. leaf apex </li></ul><ul><li>4. shape of the blade </li></ul><ul><li>5. leaf bases </li></ul><ul><li>6. presence or absence of petiole </li></ul><ul><li>7. leaf arrangement on the stem (phyllotaxy) </li></ul><ul><li> 8. leaf surface </li></ul><ul><li>(but of these may also used to classify the compound leaves) </li></ul>
  8. 8. Classification by Leaf Arrangement on the Stem Opposite : If each node has a pair of leaves 180 degrees apart. Alternate : Each node has a single leaf and the leaves of adjacent nodes point different directions Whorled : If a node has three or more leaves attached.
  9. 9. <ul><li>rosette is a circular arrangement of the leaves, with all the leaves at a single height. Often, perennial plants whose foliage dies and the remaining vegetation protects the plant. Internodes are often shortened getting the leaves closer together, as in lettuce and dandelion. This is an example of a modified stem. </li></ul>
  10. 10. <ul><li>As a stem grows, leaves tend to appear arranged around the stem in a way that optimizes yield of light. In essence, leaves form a helix pattern centred around the stem, either clockwise or counterclockwise , with (depending upon the species) the same angle of divergence. There is a regularity in these angles and they follow the numbers in a Fibonacci sequence : 1/2, 2/3, 3/5, 5/8, 8/13, 13/21, 21/34, 34/55, 55/89. This series tends to a limit of 360° x 34/89 = 137.52 or 137° 30', an angle known mathematically as the golden angle . In the series, the numerator indicates the number of complete turns or &quot;gyres&quot; until a leaf arrives at the initial position. The denominator indicates the number of leaves in the arrangement. </li></ul>
  11. 11. <ul><li>This can be demonstrated by the following: </li></ul><ul><li>alternate leaves have an angle of 180° (or 1/2) </li></ul><ul><li>120° (or 1/3) : three leaves in one circle </li></ul><ul><li>144° (or 2/5) : five leaves in two gyres </li></ul><ul><li>135° (or 3/8) : eight leaves in three gyres. </li></ul>
  12. 12. Leaf Shape Bilobed Bauhinia variegata Cordate Ivy Elliptical, oval Ficus pumila Lanceolate Codiaeum variegatum Linear Iris tectorum Needle-shaped Pinus massoniana General shape
  13. 13. Oblong Ficus elastica Ovate Hibiscus rosa-sinensis   Sagittate Mikania micrantha Auriculate Arabis caucasica oblanceolate Ilex glabra spatulate Myrica pensylvanica
  14. 14. palmately lobed pinnately lobed scale-like awl-like
  15. 20. Venation (arrangement of the veins) <ul><li>There are two subtypes of venation, namely, craspedodromous , where the major veins stretch up to the margin of the leaf, and camptodromous , when major veins extend close to the margin, but bend before they intersect with the margin </li></ul>
  16. 21. <ul><li>Feather-veined, reticulate — the veins arise pinnately from a single mid-vein and subdivide into veinlets. These, in turn, form a complicated network. This type of venation is typical for (but by no means limited to) dicotyledons . </li></ul><ul><li>1. Pinnate-netted, penniribbed, penninerved , penniveined; the leaf has usually one main vein (called the mid-vein), with veinlets, smaller veins branching off laterally, usually somewhat parallel to each other; </li></ul><ul><li>eg Malus (apples). </li></ul>
  17. 22. <ul><li>2.Palmate-netted, palmate-veined, fan-veined ; several main veins diverge from near the leaf base where the petiole attaches, and radiate toward the edge of the leaf; e.g. most Acer (maples). </li></ul>Palmate-veined leaf
  18. 23. <ul><li>Parallel-veined, parallel-ribbed, parallel-nerved, penniparallel — veins run parallel for the length of the leaf, from the base to the apex. Commissural veins (small veins) connect the major parallel veins. Typical for most monocotyledons , such as grasses . </li></ul>By Brann on Flickr
  19. 24. <ul><li>Dichotomous — There are no dominant bundles, with the veins forking regularly by pairs; found in Ginkgo and some pteridophytes . </li></ul>By greenwoman46 on Flickr
  20. 27. Leaf margins <ul><li>The leaf margin is characteristic for a genus and aids in determining the species. </li></ul><ul><li>1. entire: even; with a smooth margin; without toothing </li></ul><ul><li>2. ciliate: fringed with hairs </li></ul><ul><li>3. crenate: wavy-toothed; dentate with rounded teeth, such as Fagus (beech) </li></ul>
  21. 28. <ul><li> 3. dentate : toothed, such as Castanea (chestnut) </li></ul><ul><li> a. coarse-toothed: with large teeth </li></ul><ul><li>b. glandular toothed: with teeth that bear </li></ul><ul><li>glands. </li></ul><ul><li>4. denticulate: finely toothed </li></ul><ul><li>doubly toothed: each tooth bearing smaller teeth, such as Ulmus (elm) </li></ul><ul><li>5. lobate : indented, with the indentations not reaching to the center, such as many Quercus (oaks) </li></ul><ul><li>6. palmately lobed : indented with the indentations reaching to the center, such as Humulus (hop). </li></ul>
  22. 29. <ul><li>7. serrate: saw-toothed with asymmetrical teeth pointing forward, such as Urtica (nettle) </li></ul><ul><li>8. serrulate: finely serrate </li></ul><ul><li>9. sinuate: with deep, wave-like indentations; coarsely crenate, such as many Rumex (docks) </li></ul><ul><li>10. spiny: with stiff, sharp points, such as some Ilex (hollies) and Cirsium (thistles). </li></ul>
  23. 31. Simple Leaves - Margin Structure
  24. 34. Types of compound leaves: <ul><li>Pinnately compound – where the leaflets are attached along the side of the stalk or rachis </li></ul><ul><li>palmate - having the leaflets arranged round a single point like fingers </li></ul>
  25. 35. Other types of compound leaves
  26. 36. Recognize specialized leaves <ul><li>Shade Leaves </li></ul><ul><li>- Leaves in the shade receive less total light, thus tend to be thinner and have fewer hairs than leaves on the same tree exposed to direct light. </li></ul><ul><li>Leaves of Arid Regions </li></ul><ul><li> - Many have thick, leathery leaves and few stomata. </li></ul><ul><li> - Some have succulent, water-retaining leaves, or dense, hairy coverings. </li></ul>
  27. 37. Other structures for comparison
  28. 40. <ul><li>Tendrils </li></ul><ul><li>- Modified leaves that curl around more rigid objects helping the plant to climb or support weak stems. </li></ul><ul><li>1. Become coiled like a spring as they develop. </li></ul><ul><ul><ul><li>2. When contact is made, the tip curls around the object, and the direction of the coil reverses. </li></ul></ul></ul><ul><ul><ul><li>example: Makahiya </li></ul></ul></ul>
  29. 41. <ul><li>Spines, Thorns, and Prickles </li></ul><ul><li>1. Spines - Modified leaves designed to reduce water loss and protect from herbivory. </li></ul><ul><li>2. Thorns - Modified stems arising in the axils of leaves of woody plants. </li></ul><ul><li>3. Prickles - Outgrowths from the epidermis or cortex. </li></ul>
  30. 43. <ul><li>Storage Leaves - Succulents </li></ul><ul><li>Flower-Pot Leaves - Urn-Like Pouches </li></ul><ul><li>Window Leaves - Leaves buried in ground. </li></ul><ul><li>Reproductive Leaves - New plants at tips. </li></ul><ul><li>Floral Leaves - Bracts </li></ul>Example of storage leaves - onion
  31. 44. Other succulent leaves Aloe mitriformis
  32. 45. Selaginella Bracts – ex Poinsettia
  33. 47. <ul><li>Insect-Trapping Leaves </li></ul>a. Pitcher Plants b. Butterworts –(Pinguicula sp)
  34. 48. d. Bladderworts b. Sundews c. Venus’s Flytrap s
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