NEET Biology Notes Morphology of Flowering Plants Stem
Stem
It is the ascending part of the axis bearing branches, leaves, flowers and fruits. It develops from the plumule of embryo of a germinating seed and bears nodes and internodes. Node is the region, where leaves arise and intemode is the region between two nodes.
Main functions of stem are as follow:
- It bears leaves, fruit, flowers and seeds in position.
- Transport water and minerals among leaves, flowers, fruits and roots.
- Stem store food as reserve food material, bears flowers for reproduction and provide support and protection to plant.
- Stem synthesize hormone, e.g. auxin.
Special features of stem are as follows:
- In many xerophytic plants like Opuntia, stem becomes green, flattened or fleshy, which carries out photosynthesis. It is called phylloclade or cladophyll.
- In some plants, short, green, cylindrical (e.g. Asparagus) or some times flattened (e.g. Ruscus) branches, limited in growth, develop from the node of stem or branch in the axil of a leaf, which are reduced to small scales which perform the functions of photosynthesis. It is called cladode.
- Some stems are thin, weak and lie prostrate on soil.
- Tendril is a thread-like, green, leafless, spirally coiled structure sensitive to touch. These help in the climbing of weak stem.
