Vascular plants are comprised of three major permanent tissues, i.e. dermal, vascular, and ground tissues. Ground tissues are plant tissues that fill in the soft parts of the plants. Ground tissues, in turn, are made up of three types of fundamental cells. These cells are parenchyma, sclerenchyma, and collenchyma cells. The most common type is the parenchyma cell. Compared with the other two, the parenchyma cell has relatively thin wall. It has primary cell wall only, which means a secondary cell wall is absent. The cell does not lose its protoplast at maturity and therefore remains alive and metabolically active.
Parenchyma cells have different functions. One of them is for food manufacturing through photosynthesis. A parenchyma cell that is photosynthetic is referred to as a chlorenchyma. A chlorenchyma has chlorophyll-containing plastids called chloroplasts. A chloroplast is a plastid that contains high amounts of green pigment, chlorophyll. Light energy is absorbed by the chlorophyll to utilize it in the production of sugars. Chlorenchyma cells are abundant in the mesophyll of leaves. They may also occur in the green stems of certain plants.
Word origin: chloro-, from Greek khlōrós (“pale green”) + chyma, from Greek énkhuma( “infusion”)