I: | Axillary buds may get modified into thorns as in gourds. |
II: | Stem tendrils develop from axillary buds as in Citrus. |
Sub-aerial modification of stem | Example | |
1. | Runner | Oxalis |
2. | Stolon | Peppermint |
3. | Offset | Pistia |
4. | Sucker | Eicchornia |