BIOLOGY HANDOUT BY: MAYA SOFIANA
PLANT TISSUES
Tissue is a collection of some cells that have similar structure and function.
Based on the activity of its composing cells, plant tissues are divided into two types,
meristem tissue and permanent tissue.
1. Meristem Tissue
Meristems or embryonic tissue is a tissue, which cells are always dividing
actively and have not differentiated yet. Based on its location, there are two types of
meristem tissue, which is located at the tip of the roots or stems and at the cambium.
a. Located at the roots or stems tip. Because of this tissue activity, the size of
plants will become length or high. It is called primary growth.
b. In dicots plants, beside the primary growing point, there is also a secondary
growing point or secondary (lateral) meristems located at the stem cambium.
Due to cambium activity, plant stem diameter will increase (width).
2. Permanent Tissue
Permanent tissue is a tissue, which the composing cells are not actively
dividing. This tissue has undergone differentiation to form a variety of more complex
tissue. This differentiation will form epidermal tissue, collenchymas, sclerenchyma,
parenchyma, xylem and phloem.
a. Epidermal Tissue. Is formed by thin compact cells. Epidermal tissue has
function to: protect tissues inside it; modify to form root hairs; secrete wax layer
(cuticle) to prevent evaporation; modify to form feathers, trichomes, or spines
as a means of protection.
BIOLOGY HANDOUT BY: MAYA SOFIANA
b. Parenchyma Tissue. Parenchyma is the basic tissue found in various organs
of plants. Cell making parenchymal tissue have a large vacuole. In addition to
the basic tissue, parenchyma tissue also has a function to establish or keep a
wide range of organic products.
c. Collenchyma Tissue. Collenchyma tissue composed of cells that experience
cellulose thickening at its corners. The function is to support or strengthen the
plant organs.
d. Sclerenchyma Tissue. Sclerenchyma tissue composed of dead cells, which
the entire cell wall has undergo thickening so becomes strong. Sclerenchyma is
stronger than collenchymas because its wall contain wood (lignin). The function
of sclerenchyma tissue is to support or strengthen particular part of the plant.
There are two types of sclerenchyma. They are sclereids or stone cells has
short in size. It can be found in peabut shells or husks that makes them hard.
Fibers have longer size than sclereids, such as the hemp can be utilized as
hemp ropes.
e. Xylem Tissue. Is the wood part of the plants. Xylem serves to drain the water
and mineral salts from the root to the leaves. Xilem tissue is composed of three
parts: vessel elements (tracheid), xylem fibers, and xylem parenchymal.
f. Phloem Tissue. Is also called sieve tubes because composes of cylindrical
cells with hole in the end like filter. The function of phloem tissue is to transport
photosynthesis product from leaves to all parts of the plants. Phloem tissue is
found in the bark. It consists of several parts as follows: sieve tubes,
companion cells, parenchymal floem and floem fibers.
BIOLOGY HANDOUT BY: MAYA SOFIANA
PLANT ORGAN
1. Root (Radix)
In higher-level plants, the roots is always embedded in the ground, only a few
plant species that live as epiphytes (attached). The process of differentiation of
the root includes the development of specific structures. Specific structures, which
resulted from differentiation process, will form several layers. From the outer layer
inward, they are epidermis, cortex, endodermis, and stele.
Epidermis is the outermost layer composed by a layer of thin cells that
compact arranged allowing bypassed by water. Some parts of the epidermis
undergo modification into the hair roots. Has function to expand the absorption
area of water and minerals salts.
Cortex is composed of several layers of parenchyma cells. The cortex serves
as a place to store food reserves.
Endodermis is a layer of cells located next to the cortex. Endodermis cell wall
will have thickening cork substance. When it is observed under the microscope,
the thickening looks like points of the cork called Casparian strip. Stele (vascular
cylinder) is located next to the endodermis.
2. Stem (Caulis)
Morphological structure of the stem is trunk, branches and twigs. In stem,
there are nodes that served as a place to attach the leaves. Stem anatomical
structure is slighty different from the root. The difference is the stem do not have
the endodermis so the structures from the outer are epidermis, cortex and stele.
Epidermis is formed by a thin layer of cells, arrange tight and the cell wall
covered by cuticle. Cuticle is useful to reduce evaporation so it protects the stem
from the drought.
Cortex is composed of parenchyma cells, thin walled, loose and disorganized
arrangement. The cells in the cortex contain starch called phloeterma (starch
glove).
Stele is a patt that located inside the cortex or the center of the stem.
According to arrangement of xylem and floem, several types of vascular
bundles are amphicribal (xylem lies in center surrounded by phloem, example
Pterydophyta), amphivasal (phloem is surrounded by xylem, example Cordyline),
close collateral (xylem lays inwards facing pith and phloem lies outwards facing
the cortex, example monocot plants), open collateral (xylem lies inwards facing
pith and phloem lies outwards facing the cortex, example dicot plants),
BIOLOGY HANDOUT BY: MAYA SOFIANA
bicollateral (xylem is between outside and inside the phloem, example
solanacea).
3. Leaf (Folium)
Leaf has function as follows: place to photosynthesis, place of water
excretion, exchange place of CO2 and O2 (respiration). Anatomical structure of
leaves shows the part composing the leaf as follows:
a. Epidermis: Epidermis undergoes modification form into stomata. Leaf epidermis
may undrgo modification to be trichome (hair)
b. Mesophyll: consist of parenchyma cell arranged tenuous and have plenty of
space between the cells.
c. Vascular bundle: find in the leaf vein that serves a leaves transportation tool anf
for strengthen leaves.
d. Additional tissue: consist of specialized cells that has present in the leaf
mesophyll, such as crystal cells and glands.
Table differences on Monocot and Dicot Leaves
No Differentiating Factor Dicot Leaves Monocot Leaves
1. Morphology Various shapes with Mostly have linear or ribbon
plamately netted venation shape with parallel venation
or pinnately netted
venation
2. Anatomy Epidermis and cuticle, Epidermis and cuticle,
stomata, mesophyll. stomata, mesophyll.
The mesophyll lies
between the upper and The mesophyll lies in the
lower epidermis. Most of hollows between the leaf
mesophyll is divided into veins.
two distinct layer , namely
palisade (contain The mesophyll do not
chlorophyll) and spongy experience differentiation.
(contain chloroplast)
