In opposite phyllotaxy, how are leaves arranged at a node?

In opposite phyllotaxy, how are leaves arranged at a node?

• A. A pair of leaves arise at each node and lie opposite to each other
• B. A single leaf at each node
• C. More than two leaves at a node
• D. Leaves arranged in a spiral

Answer: (A)

Opposite phyllotaxy means leaves appear in pairs at each node, with the two leaves directly opposite one another on the stem. So at every node you see a pair of leaves that are 180 degrees apart. Often, successive pairs are rotated 90 degrees, giving a decussate pattern. This differs from single leaves at each node (alternate arrangement), more than two leaves at a node (whorled arrangement), or leaves arranged in a spiral around the stem.

Opposite phyllotaxy means leaves appear in pairs at each node, with the two leaves directly opposite one another on the stem. So at every node you see a pair of leaves that are 180 degrees apart. Often, successive pairs are rotated 90 degrees, giving a decussate pattern. This differs from single leaves at each node (alternate arrangement), more than two leaves at a node (whorled arrangement), or leaves arranged in a spiral around the stem.