Underground Stem Modifications
As the name suggests, these are present underground. They serve various purposes such as storage of food, propagation and perennation. They can be identified from roots by the presence of nodes and internodes. They help in propagation through asexual reproduction and help the plant survive a period of dormancy. They provide protection from grazing by animals and environmental stress.
Rhizome – It runs parallel to the ground, the upper portion can produce scaly leaves and the bottom portion can give rise to adventitious roots. They contain, nodes, internodes and buds.
They store food.Examples: Ginger, turmeric.Banana contains rootstock, which is rhizome growing vertically.
Bulb – Stem is reduced and surrounded by scale leaves, modified bulbs can be seen.Examples: Tulips, Lilies, Daffodils, Onion, Garlic
Corm – It is a short upright stem, covered with scaly leaves. It is hard as compared to bulbs.Examples: Colocasia, Yam, Saffron
Tuber – Here the terminal of the stem is fleshy and stores food. The stem contains nodes and internodes but due to swelling, they are not very distinct. Presence of scaly leaves at nodes can be seen as eyes or scars.Examples: Potato, Artichokes
