Question

Explain the underground stems.

[Review question: Pg. No: 79]

Answer 1

here are some stems that grow under the ground to store food. These underground stems swell and become thick.
There are four types of underground stems:

1. Rhizome.
2. Corm
3. Tuber
4. Bulb

(i) Rhizome : It is an underground thick stem with nodes and intemodes with scale , leaves at the node. It grows horizontally and has an irregular shape. Rhizome have buds. It gives rise to new stem and leaves.
E.g. Ginger and Turmeric.

(ii) Corm: This underground stem is round in shape and flat at the top and bottom. It is a condensed form of rhizome and bears one or more buds in the axils of scale leaves. Daughter plants arise from their buds. E.g. Colocasia.

(iii) Tuber: It is an enlarged, spherical underground stem that stores food. It has many dormant buds on its surface known as “Eyes”. If we plant a part of tuber with the bud, it grows into a new plant. E.g. Potato.

(iv) Bulb: It is condensed stem which is disc like and stores food in the fleshy leaves. The bulb has two types of leaves.

1. Fleshy Leaves
2. Scaly Leaves

The upper part of the stem has a terminal bud and it is covered by many scaly leaves, the inner fleshy leaves store food as seen in Garlic and Onion