Stem Modifications in Angiosperms

On the basis of the position of the soil, stems are of three types:

• Underground stem: The branch or part of the stem which intruses inside the soil is called underground stem. These  stems store the food in the stem, node, internode, bud and scale leaf are found. Examples- banana, potato, colocasia etc.
• Sub aerial stem : If a few part of stem is inside the soil and rest is in air then such stem is called subaeriala stem. Examples-Grass root, water plant, etc.
• Aerial stem : The stem which is completely confined and localized in air and entirely outside from the soil then it is called aerial stem. In this type of stem branches, leaves, node, internodes, buds flower-fruit etc are found. Examples-Grapes, lemons, roses etc.

To perform some specific works, stems sometimes do exclusive  works other than common work then shapes and sizes of the stems are changed and it is called modifications of stems. Usually there exists three types of modifications in the stems-

Underground modifications

In the diverse conditions, underground stems store their food inside the stems and become thickened and tuberous. There are various types of modifications occur in underground stem-

• Stem tuber- Potato
• Bulb – Onion, garlic, tulips, lilies etc.
• Corm – Gladiolus, crocus, saffron etc.
• Rhizome—Ginger, turmeric, arrow root etc.

Sub aerial  modifications

There are various types of modifications exists in such types of stem-‘

• Runner – Grass root, mereilia etc.
• Stolon – Mint, jasmine, straberi etc.
• Offset – Water plant, pestia etc.
• Sucker – Roses, gilly flower etc.

Aerial modifications

There also occur various types of aerial modifications-

• Stem tendril – Grape.
• Stem thorn – Lemon, roses, jujube, plum or Chinese date.
• Phylloclade – Cactus.
• Bublis – Ruscus.