Sclerenchyma tissues are long and narrow as the walls are thickened due to lignin (a chemical substance which acts as cement and hardens them).

Aerenchyma is a special tissue found in hydrophytes (e.g. Hydrilla, Potamogeton, etc.) and some land plants (e.g. petiole of banana, Canna), formed by parenchyma cells. They make a network by leaving wide air spaces (air cavities) for the gaseous exchange ...

Mixture is constituted by more than one substance in any ratio. For example, water, soil, polluted air, etc.