The different types of
plant cells found in six
organs of the plant body
MERISTEMATIC TISSUE
A.K.A MERISTEMS
:Characterized by small cells, thin cell walls, large cell nuclei,
absent or small vacuoles and no intercellular spaces.
:Apical (located at root and shoot tips), lateral (in the vascular and
cork cambia), and intercalary (at internodes, or stem regions
between the places at which leaves attach, and leaf bases,
especially of certain monocotyledons)
:Primary meristematic tissue helps the plant increase in length or
vertical growth, meaning it helps the plant grow up toward the sun
and down into the soil. Secondary meristematic tissue helps the
plant increase the girth or lateral growth of its stems, branches,
and roots.
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PARENCHYMA
:Composed of thin-walled cells and makes up the
photosynthetic tissue in leaves, the pulp of fruits, and
the endosperm of many seeds.
:Found in many parts of the plant body.This is most
commonly found in the medullary rays, the pithand
the cortex of the wood. It is also found as a packing
tissue phloem and xylem. It is mostly found in the
softer parts of the plants.
:They function in storage, photosynthesis, and as the
bulk of ground and vascular tissues
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COLLENCHYMA
:composed by elongated living cells of uneven primary thick
walls, which possess hemicellulose, cellulose, and pectic
materials.
:found immediately under the epidermis, young stems,
petioles, and leaf veins. Also, it has been seen in avocado
fruit hypodermis.
:Provides support, structure, mechanical strength, and
flexibility to the petiole, leaf veins, and stem of young plants,
allowing for easy bending without breakage.
SCLERENCHYMA
:have thick, lignified secondary walls, lack cell
contents at maturity, and occur throughout all plant
tissues. These features make sclerenchyma tissues
hard, rigid, and somewhat brittle.
:They are found mainly in the cortex of stems and in
leaves.
:Sclerenchyma tissue, when mature, is composed of
dead cells that have heavily thickened walls
containing lignin and a high cellulose content (60%–
80%), and serves the function of providing structural
support in plants.
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GUARD CELLS
:Guard cells are cells surrounding each stoma. Each
guard cell has a relatively thick cuticle on the pore-side
and a thin one opposite it.
:Guard cells are surrounded by stomatal pores and are
located in leaf epidermis.
:Guard cells control influx and efflux of CO2 and water
from leaves, respectively.
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TRICHOME CELLS
:Trichomes are either glandular or non-glandular.
:Different types of non-glandular trichomes can be
found in different locations of a single plant. For
instance, whole some of these can be found on the
leaf of the plant (unicellular non-glandular trichomes
on Coridothymus capitatus) two-celled trichomes
can be located at the base of abaxial side of the
leaf.
:Can be insulating by keeping frost away from leaf
cells. They can help reduce evaporation by
protecting the plant from wind and heat. In many
cases, trichomes protect plants from herbivorous
insects that may want to feed on them.
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EPIDERMAL CELLS
:Leaf epidermal cells are usually irregular or
polygonal in shape.
:In plant’s leaves, epidermal cells are located on
the upper and lower part of the leaf where they
form the upper and lower epidermis. The cuticle,
however, is located on the upper epidermis for the
most part. In plants, this is the outermost part that
is secreted by the epidermis.
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:Forms a boundary between the plant and the
external environment, serves several functions: it
protects against water loss, regulate gas
exchange, secretes metabolic compounds, and
(especially in roots) absorbs water and mineral
nutrients.
FIBER CELLS
:They are long, cylindrical, tubular cells with tapering
conical ends, unbranching, and not perfectly round in
cross section. The number of fibers varies from 50 to
300 in each fasciculus (bundle).
:They often occur in bundles or strands and can be
found almost anywhere in the plant body, including
the stem, the roots, and the vascular bundles in
leaves.
:function as support tissue in plant stems and roots.
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PHLOEM CELLS
A.K.A transfer cells and border
parenchyma cells
:Phloem consists of living cells arranged end to end. Phloem
vessels contain cytoplasm, and this goes through the holes in
the sieve plates from one cell to the next.
:Located near the finest branches and terminations of sieve
tubes in leaf veinlets, where they also function in the transport
of foods.
:Phloem transports sucrose and amino acids up and down
the plant. This is called translocation.
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XYLEM CELLS
:The xylem tracheary elements consist of cells known as
tracheids and vessel members, both of which are
typically narrow, hollow, and elongated.
:Can be found: in vascular bundles, present in nonwoody plants and non-woody parts of woody plants. in
secondary xylem, laid down by a meristem called the
vascular cambium in woody plants.
:Xylem, plant vascular tissue that conveys water and
dissolved minerals from the roots to the rest of the plant
and also provides physical support.
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PHLOEM AND XYLEM CELLS
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SIEVE TUBES
:Consist of sieve elements which are elongated cells,
connected to each other via sieve plates to form a continuous
tube system that spreads out through the entire plant. Mature
sieve elements contain structural phloem specific proteins (Pproteins), mitochondria, ER, and sieve elements plastids.
:It is found in the phloem of all the angiosperms and flowering
vascular plants. It is located inside sieve cell.
:Sieve tube members maintain cells and transporting
necessary molecules with the help of companion cells. The
sieve tube members are living cells (which do not contain a
nucleus) that are responsible for transporting carbohydrates
throughout the plant.
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COMPANION CELLS
:Have dense protoplasts which contain the typical organelles of
plant cells, including chloroplasts and many ribosomes.
:found within the phloem of flowering plants.
:Its function is uncertain, though it appears to regulate the
activity of the adjacent sieve element and to take part in loading
and unloading sugar into the sieve element.
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THANK
YOU!
-DANIELLE SKYLAR DALMAN PAWAI
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Extra resources
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