Leaf Arrangements

forest

  • Alternate: Leaves occur on alternating sides of the twig at varying heights.
    3-20

  • Opposite: Opposite leaves grow at the same position of the twig, but on opposite sides.
    2-33

  • Simple: For simple leaves, one whole leaf grows from its individual bud, attached directly to the stem.
    3-19

  • Compound: Refers to broadleaf trees. Multiple leaflets grow from one common stem or point. If one leaflet were to fall off, it would not be replaced, only if the whole leaf fell off would it regrow. This is demonstrated by the position of the bud at the base of the leaf (not the leaflet), i.e. at the point of attachment to the main twig.
    3-5

  • 2-ranked: There are two distinct rows of leaves may be seen while looking down the stem. Commonly occurs in one plane.
    1-13

  • Spirally Arranged:Multiple rows of leaves may be seen while looking down the stem. Specifically referrs to coniferous trees.
    1-20

  • Decussate:Refers to coniferous trees where two leaves grow from one node alternating in opposite and perpendicular planes. This is commonly seen in false cedars.
    1-31

  • Single: Again referring to coniferous trees.Leave occur singly, i.e. one leaf grows from its own point on the stem.
    1-15

  • Bundles: Refers to coniferous trees where multiple needles grow from the same point.
    3-30

  • Flat Sprays: Notice the platter like appearance of the branch of leaves.
    3-8

Terms to Know 
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Coniferous Species 
Broadleaf Species