The epidermis is "epi“in Greek meaning "over" or
"upon", which together with the dermis forms skin.
The epidermis is a single layered group of cells that
covers plant’s leaves, flowers, roots and stems.
Functions of epidermis
It forms a boundary between the plant and the
It protects against water loss,
regulates gas exchange,
secretes metabolic compounds,
Absorbs water and mineral nutrients (especially in
The epidermis of most leaves shows dorsoventral
anatomy: the upper (adaxial) and lower (abaxial)
surfaces have somewhat different construction and
may serve different functions.
Woody stems and some other stem structures produce
a secondary covering called the periderm that replaces
the epidermis as the protective covering.
The epidermis is the outermost cell layer of the
primary plant body. In some older works the cells of
the leaf epidermis have been regarded as
specialized parenchyma cells, but the established
modern preference has long been to classify the
epidermis as dermal tissue, whereas parenchyma is
classified as ground tissue. The epidermis is main
component of the dermal tissue system of leaves and
also stems, roots, flowers, fruits, and seeds; it is
Cells of epidermis;
The cells of the epidermis are structurally and
Most plants have an epidermis that is a single cell layer
Some plants which have periclinal cellular division
within the protoderm of the leaves, have an epidermis
with multiple cell layers.
Sharp projections modified on plant organ.
An obvious adaptation against predation is plant
Plant armature is properly termed as an emergence.
(These may be absent in reproductive structures.)
There are some plant’s emergences are discussed
which are as;
Root hairs are lateral extensions of a single cell and
Root hairs vary between 5 and 17 micrometres in
diameter, and 80 to 1,500 micrometres in length.
Root hairs can survive for 2 to 3 weeks and then die off.
At the same time new root hairs are continually being
formed at the top of the root. This way, the root hair
coverage stays the same.
A sharply pointed tough or woody structure is called
Some spine’s types are as;
stem spine: a spine is a modified stem axis (it may have
leaf scars), which becomes determinate (i.e., it has a very
limited period of growth).
leaf spine: a spine is a modified leaf or leaf
primordium; also there may be a leaflet spine.
shoot spine: a spine is a modified stem and leaves.
stipular spine: a spine is a sharp, modified stipule or
petiolar spine: a spine is a modified petiole that
remains after the blade is shed.
root spine: a spine is a modified root that loses its
meristematic apex and root cap.
bract spine: a spine is a modified leaf (bract) positioned
below a flower or part of an inflorescence.
Trichomes ( from the Greek trikhōma meaning
"hair") are fine outgrowths or appendages on plants.
Aerial surface hairs
A small sharp pointed spine is
known as prickle.
Some other emergences of plants
leaf emergence: a sharp projection is from the blade or
petiole of a leaf, most commonly arising on the top or
bottom of a principal vein or along the petiole.
stem emergence: a sharp projection is from stem axes,
often associated with climbing or scambling habit.
fruit emergence: woody projection, sometimes with
hooks, is on the outer fruit wall.
Inflorescence emergence: projection is from a bract.
bark emergence: projection is located on bark of the
trunk or its branches.
Functions of emergences;
Plant emergences have some functions which are;
• Protect from animals e.g spines.
• These are the obvious adaptations against predation .
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