Answer:
We can determine the past arrangement of leaves on a bare twig by looking at the arrangement of axillary buds and leaf scars.
Step-by-step explanation:
- The arrangement of leaves on a branch or stem is called phyllotaxy.
- Leaves are formed at stem nodes.
- They bear axillary bud on their axil.
- Axillary bud give rise to flowers and new branches.
- When leaves shred off we can determine their phyllotaxy by looking at the axillary buds on the nodes.
- When leaves fall off the stem, they leave scars at the nodes, these scars can also be considered to find out the attachment of leaves and phyllotaxy.
Common leaf arrangements are:
- Alternate.- When one leaf arises at each node and successive leaves develop on alternate sides .se.g. As seen in Barberry
- Opposite- When two leaves arise at one node and on the opposite side of the stem. E.g as seen in maple.
- Whorled.- When three or more leaves arise at a node forming a whorl.