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Tissues
The Plant Cell
• All living organims are composed of cells. The cells
are their building blocks.
• Plant cells are basic building blocks of plants
• Cells can specialize to perform specific functions
• A group of cells working together form a tissue.
• These tissues are specialized to perform specific
plant functions.
• Levels of organization: atoms > molecules > cells >
tissues > organs > whole plant
Plant Tissues Types
All plant organs (roots, stems, leaves) are composed of
the same tissue types. The tissues that originated in
embryo’s body are called primary tissues.
There are three types of tissue:
1. Dermal – outermost layer
2. Ground – bulk of inner layers
3. Vascular – conducting tissue, transport
1. Dermal tissue
• Epidermis is the outermost layer of cells. It
is a single layer of cells without chloroplasts.
• The functions of the epidermis includes,
absorption, protection and gas exchange.
• In stems and leaves, the epidermis has a
cuticle, a waxy layer that prevents water loss.
Its thickness varies in the different plants.
The Cuticle
The Stomata
In addition, the epidermis may
have specialized cells with
different functions.
In the epidermis of leaves and
sometimes stems, you find a
specialized group of cells
called stomata.
These are specialized
for gas exchange
Dermal tissue
• Another group of specialized cells
found in leaves and stems are the
Trichomes or hairs (fuzzy look).
These may release chemicals
(for aroma, defense), reflect light, etc.
More trichomes
Surface of Lavender, including hairs and glands.
And more.....
Ground tissues
• Makes up the bulk of plant organs.
• Functions: Photosynthesis, storage and support
• Three different ground tissues are present in
plants:
• Parenchyma
• Collenchyma
• Sclerenchyma
The Parenchyma
Photosynthetic
parenchyma makes the
main tissue in the
leaves of plants. Ex:
Elodea
Photosynthetic
parenchyma in
Syringa (lilac) leaf
cross section.
Ground tissue
• In roots and seeds, parenchyma tissue
often stores sugars and starch
(for example: yams, sweet potato, etc.)
You’re not a
yam, you’re a
sweet potato!
Storage in Bean Seeds
(endosperm). IKI stain
Hey!
I yam
what I
yam,
man!
Parenchyma in
storage cells with
starch grains
known as
AMYLOPLASTS.
Parenchyma in Capsicum
(red pepper) with Licopene
pigment granules known as
CHROMOPLASTS.
The Chollenchyma
The collenchyma is
made of cells with
unequally
thickened walls. It
provides mild
support. For
example the ribs in
a celery stalk.
The Sclerenchyma
Vascular tissues
• Transports water and organic materials (sugars)
throughout the plant
• Xylem – transports water and
dissolved ions from the root
to the stem and leaves.
• Phloem – carries dissolved sugars
from leaves to rest of the plant
The Xylem
The Phloem