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The Importance of Leaf Arrangement
Leaf arrangement is one of the first steps in helping to narrow
down the options of woody plant identification. There are two types
of arrangement that are usually discussed, arrangement of leaves
at a node, and arrangement of leaves along the stem. Here we are concerned with arrangement of leaves at a node.
Arrangement at Nodes
Alternate: Leaves or Stems situated one at a node. Leaves
can also alternate in a distichous pattern along only two sides
of the stem.
Opposite: Stems or leaves appear across from one another
at the same node; opposite leaves may also appear decussate (pairs alternating
at 90º angles at every node).
Subopposite: Leaves appear near opposite but not exactly
opposite at a nodee.
Whorled: Three or more leaves arising at a node.
Leaf Arrangement Illustration (pdf)
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