University:
California State University, Los Angeles
Course:
BIOL 1010 | General Biology
Academic year:

2022
Views:

398

Pages:

1
Author:

Firly G

Strengthening Tissue In the plant body, there is a need for strengthening tissue to strengthen the body. Therefore, plants need strengthening or supporting tissue, which is also called mechanical tissue. This mechanical tissue generally consists of thick-walled cells and contains lignin and other substances. These substances give hard properties to the cell walls. Based on its shape and properties, mechanical tissue is divided into collenchyma and sclerenchyma. 1) Collenchyma tissue This tissue is the main reinforcement for plant organs which are still actively carrying out growth and development. Collenchyma is a homogeneous tissue composed of collenchyma cells. Collenchyma is generally located under the epidermis of stems, leaf stalks, flower stalks, and leaf veins. Collenchyma is rarely found in roots. Collenchyma cells usually extend parallel to the center of the organ where the collenchyma is found. Collenchyma cell walls do not contain lignin, but contain cellulose, pectin and hemicellulose.Sometimes in collenchyma cells there are chloroplasts so they also function in photosynthesis.Collenchyma cells usually experience local thickening of their cell walls. Based on the location and shape of the thickening, collenchyma is divided into three types, namely angular collenchyma, lamellar collenchyma, and lacunate collenchyma. Angular (corner) collenchyma experiences thickening at the corners. Lamellar collenchyma (board) experiences thickening of the tangential cell walls only. Meanwhile, lacunate collenchyma (lacuna) experiences thickening on the surface of the intercellular spaces. 2) Sclerenchyma tissue. This tissue is also a reinforcing tissue, but it is only found in plant tissue that no longer carries out growth and development. Sclerenchyma tissue consists of dead cells. The cell walls are very thick and strong because they contain lignin (the main component of wood). The cell walls experience primary thickening and secondary thickening by lignin.Based on its shape, sclerenchyma is divided into two, namely sclerenchyma fibers which are shaped like long threads, and sclereids (stone cells). Sclereids are found in transport bundles, between parenchyma cells, stem cortex, leaf petioles, roots, fruit and seeds.Sclerenchyma functions to strengthen mature plant parts. Sclerenchyma also functions to protect the soft parts that are deeper, for example the skin of castor beans, coconut shells and walnuts. into phloem tissue and xylem tissue.