2. A group of cells which are similar in origin; similar in
structure and similar in function are called simple
permanent tissue. They are of four types:
Parenchyma
Collenchyma
Sclerenchyma
Epidermis
PLANT TISSUE
3.
4. Parenchyma cells have thin primary walls and usually remain alive
after they become mature.Parenchyma forms the "filler" tissue in the
soft parts of plants. Collenchyma cells have thin primary walls with
some areas of secondary thickening.
Collenchyma tissues are mainly found under the epidermis in young
stems in the large veins of leaves. The cells are composed of living,
elongated cells running parallel to the length of organs that it is
found in. Collenchyma cells have thick cellulose cell walls which
thickened at the corners
SCLERENCHYMA CELLS
Mature sclerenchyma cells are dead and have secondary cell walls
thickened with cellulose and usually impregnated with lignin. In
contrast to collenchyma, which is pliable, sclerenchyma is elastic.
The cell cavity or lumen is very small or it may disappear completely.
5. EPIDERMIS
The entire surface of the plant consists of a
single layer of cells called epidermis or surface
tissue. The entire surface of the plant has this
outer layer of epidermis. Hence it is also called
surface tissue. Most of the epidermal cells are
relatively flat. The outer and lateral walls of the
cell are often thicker than the inner walls. The
cells forms a continuous sheet without inter
cellular spaces. It protects all parts of the plant.
