noun, plural: ground tissues
(botany) Any of the non-dermal, non-vascular tissue of vascular plants
A ground tissue is a plant tissue other than those of the dermal tissues and the vascular tissues. It arises from the ground meristem. It fills in the soft parts of the plants, such as cortex, pith, pericycle, etc. There are three fundamental types of cells that make up a ground tissue, i.e. parenchyma, sclerenchyma, and collenchyma cells. These cells are classified according to the nature, morphology, and composition of the cell walls.
Parenchyma cells have relatively thin primary walls. Most of them continue to be alive even upon reaching maturity. They are the most common type of filler cells in ground tissues. In stems, they are found in cortex and pith. In roots, they fill the cortical region. They also form the mesophyll of leaves. The cells of the endosperm of seeds and the pulp of fruits are also parenchymatous. The parenchyma cells have a variety of functions. Some of their major functions include photosynthesis, storage, and secretion. The collenchyma cells are cells with a relatively thicker primary cell wall. The sclerenchyma cells, in contrast, have a secondary cell wall. Apart from the primary cell wall, the sclerenchyma cells deposit a secondary cell wall between their primary cell wall and plasma membrane. They are dead at maturity and their walls are lignified. Both collenchyma and sclerenchyma cells provide structural support to the plant. However, the sclerenchyma cells are the main supporting cells in many plants.