simple tissue

In biology, a tissue is a group of similar cells that work together to perform a specific function. Plants have several types of tissues, including:1

• Parenchyma: These are living, thin-walled cells adaptable to various functions like photosynthesis, secretion, and food storage. They form the soft tissues of fruits and the internal layers of leaves and stems.2
• Collenchyma: This is a living support tissue with irregularly thickened cell walls made of cellulose. It provides strength and flexibility, especially in growing plant organs, and is found in stems and leaves. The "strings" in celery stalks are an example.3
• Sclerenchyma: This is a hard, woody tissue composed of dead cells with heavily thickened, lignified walls. It provides rigid support and is found in non-growing parts of plants, such as bark and mature stems. Examples include fibers used in textiles and sclereids that give pears their gritty texture.45

These tissues are fundamental to a plant's structure and survival.24