Sclerenchyma is present in the husk of coconut.
Sclerenchyma is a type of simple tissue categorized under permanent tissues. Permanent tissues are the tissues in which cell division is ceased. Sclerenchyma is characterized by the presence of thickened lignified cell walls providing the plant with mechanical support and imparting the property of being waterproof. These tissues cause the plant to be stiff and hard and are found in the stems, hard covering of seeds and nuts, girdling vascular bundles, in leaf venations.
These tissues have a chemical named lignin, which acts as a cement, causing the hardening.