A tissue composed of relatively elongated cells with thickened nonlignified primary cell walls. Collenchyma is sometimes considered to be * parenchyma with exceptionally thick cellulose cell walls, specialized as a supporting and strengthening tissue in organs lacking (or almost lacking) secondary growth. Examples are young herbaceous stems and leaves. The thickened cell walls of collenchyma cells are sometimes used as a supply of cellulose for the other tissues in times of shortage. The wall thickenings may be mainly on the tangential walls (lamellar collenchyma), in the corners of the cells (angular collenchyma), or adjacent to the intercellular spaces (lacunar collenchyma). Compare sclerenchyma. |
