Plant Stems
Basic Structure of Plant Stems
- Plant stems are integral parts of the plant’s structure, providing support and helping to spread leaves wide for sunlight exposure.
- Stems consist of nodes (where leaves, buds, and branches attach) and internodes (the sections in between).
- The apical meristem (growing tip) is found at the end of the stem, crucial for the primary growth of the plant.
The Role and Function of Plant Stems
- Stems connect roots and leaves, serving as a conduit for water, minerals, and sugars to move within the plant. This movement of substances is termed translocation.
- In photosynthesis, the stem acts as a highway for glucose (product of photosynthesis) to move from leaves to other parts of the plant.
- Stems also have a role in storage, with some stems like tubers, rhizomes, and bulbs storing carbohydrates and water.
Key Cells and Tissues in Plant Stems
Epidermal Cells
- Found on the exterior of the stem. They produce a waxy, waterproof layer called the cuticle to prevent water loss.
Vascular Tissue
- Made up of xylem and phloem cells that specialise in the transport of water, minerals and food in the plant.
- Xylem transports water and dissolved minerals from roots to leaves.
- Phloem transports sugars (products of photosynthesis) from leaves to other parts of the plant.
Parenchyma Cells
- Most common type of plant cell. They play diverse roles, including storage, photosynthesis, and aiding in the repair and regeneration of the plant.
Sclerenchyma Cells
- Provide support and strength to the plant stem. They are often located near vascular tissues and are characterised by their thick, rigid cell walls.
Stem Modifications
- Some plants have adapted their stem structures for specific purposes. For example, climbing plants have twining stems or tendrils to help them climb.
- Cacti have an expanded stem that stores water and a reduced leaf structure to limit water loss.