This document discusses two types of simple plant tissues: collenchyma and sclerenchyma. Collenchyma tissue provides strength and support to growing shoots and leaves through cells with thickened corners. It allows for close packing while maintaining flexibility. Sclerenchyma tissue consists of hard, lignified cells that provide structural support to mature plant regions. The two main types are fibers, which occur in bundles and strands, and sclereids, which come in various shapes and sizes and contribute to plant hardness. Both collenchyma and sclerenchyma tissues play crucial mechanical roles in supporting and strengthening plant structures.