Question

What is pseudostem? Give an example.

Answer 1

Hint: Stem is the aerial axis that bears leaves, fruits and supports the plant. The pseudostem is formed when leaves wrap around by overlapping and thus takes over the function of the stem. The pseudostem is found in Banana.

Complete answer:The stem is the aerial erect axis of the body which develops from the plumule of the embryo of a germinating seed. The stem axis is distinguished into nodes and internodes. The stem bears leaves, buds, flowers, and seeds. Branches are exogenous in origin; the leaf-bearing part of the stem is called the shoot.
The pseudostem is a leafy part that is formed by overlapping of leaves and looks like a stem. It is fleshly and mainly consists of water, but still can support the plant. It continues to grow as leaves merge one after the other and continue to grow in height, till inflorescence is formed at the top position.
The pseudostem is found in the banana plant, which looks like a trunk. When the leaves have matured, they unwrap from the stem. Banana pseudostem has commercial importance as well, can be used as pulp and paper raw material, fibers for textiles, etc.

Note:Modifications of aerial stems are as follows-
1. Stem tendrils- which develop from axillary buds, are slender and spirally coiled and help plants to climb such as in gourds and grapevines.
2. Stem thorns- axillary buds of the stem may also get modified into woody, straight, and pointed thorns. Thorns are found in Citrus plants and can protect plants from browsing animals.
3. Cladodes- these are the green stem of limited growth, which have taken over the function of photosynthesis from the leaves. True leaves are reduced to spines or scales.
4. Example in Ruscus and Asparagus.
5. Phylloclades- these are flattened, round often succulent stems of indefinite growth that have taken over the function of photosynthesis. This is a type of adaptation to xerophytic conditions. Example- Euphoria, Opuntia.