ANATOMY
Refers to the internal structure of plants.
The plant body is made up of groups of
identical as well as complex cells.
Anatomical Characteristics Assist Us in
Understanding:
1.
The process of photosynthesis, absorption and
movement of water, as well as the translocation of food.
2.
The success and failures of horticultural practices such
as pruning, grafting and other forms of vegetative
propagation.
3.
Plant Pathology, particularly the anatomical structure of
plant parts that are attacked thus giving further insight on
the parasitic effect.
4.
Taxonomy.
Main Topics
A.
Types of Cells and Tissues
B.
Primary and Secondary Growth :
root, stem, leaf, flower, fruit and
seed
TISSUES
Meristematic Tissues
- apical meristem
- lateral meristems
- intercalary meristem
Tissue: A group of cells
that perform similar
function(s)
Non Meristematic Tissues
Simple tissues
- parenchyma
- collenchyma
- sclerenchyma
Complex tissues
- xylem
- phloem
- epidermis
- periderm
- secretory cells and
tissues
Meristematic tissue
-
-
Consists of newly formed cells, small sized, with thin cell
wall and dense protoplasm, box shaped and having six
surfaces, a large nucleus and small vacuoles
Cells are always actively dividing
When mature, the cell shape differs according to the cell
function, while the vacuoles increase in size
Meristematic cells
Apical meristem
-
found at the tip of shoots and roots
-
The plant lengthens as the apical meristem
produces new cells
** Gives rise to 3 primary meristems:
protoderm, ground meristem, and
procambium (which forms the xylem dan
phloem).
Primary meristem produces the primary
tissues
primary growth
Shoot apical meristem
Primary meristems in a shoot
apex
Root apical meristem
Lateral meristems
- Vascular
cambium and cork cambium
- Produce
tissues that increase the girth of stem and roots
- Vascular
cambium : a thin cylinder in stem and root of annuals
and perennials
-
Cork cambium : a thin cylinder in stem and root of woody
plants, found outside the vascular cambium and within the
bark of plants
- Tissues
produced from both the vascular cambium and cork
cambium are secondary tissues formed after the maturation
of the primary tissues
secondary growth
Lateral meristem
Intercalary meristem
-
Grass species (Graminae) do not possess vascular
cambium and cork cambium, instead they have
apical meristem and intercalary meristem
-
Intercalary meristems are found close to the node
region, producing primary tissues that result in the
increase in length (elongation) of stems.
Intercalary meristem
NON-MERISTEMATIC (SIMPLE TISSUE)
1. Parenchyma
tissue
consists of parenchyma
cells, the most abundant
tissue in the plant body,
found almost in all
important parts of
flowering plants.
Parenchyma cells:

Living cells, almost round in shape when first formed

The cell surface becomes even and smooth when the
thin cell wall touches each other

Can form diverse shapes and sizes, mostly having 14
surfaces

Contains a large vacuole and perhaps starch, oil, tannin,
crystals and various forms of secretion

Perform the basic metabolic functions of cells:
respiration, photosynthesis, storage and secretion

Having intercellular spaces
*parenchyma cells with large intercellular
spaces are termed arenchymas

*parenchyma cells that contain abundant
chloroplasts are termed chlorenchymas

*Transfer cells - parenchyma cells with
elongated plasmalema, large cell surface,
facilitate short distance transport between
cells
Parenchyma cells
Parenchyma
Elodea leaf showing
chlorenchymas
ARENCHYMA
2. Collenchyma tissue
- consists of living cells, the shape is more elongated
than broad
- with rather thick cell wall
- the cell wall is very flexible but strong – functions to
give support to stem, leaves and flower parts
- collenchyma cells originate from parenchyma cells
- found below the epidermis, close to the leaf midribs
and veins, or near vascular bundles
Collenchyma tissue
Stem cross section of Sambucus spp.
Collenchyma
in leaf midrib
3. Sclerenchyma tissue
- cells possess a thick and strong secondary wall
composed mainly of lignin (a polymer)
-
cells are dead (lacking a living protoplast) when
mature
-
function to provide support and sometimes
protection to the plant
-
There are two forms of sclerenchyma cells:
sclereid and fibre
fibre
Sclerenchyma
Sclereids
- originate from parenchyma cells
- cell shape : width equal length (isodiametric)
- spread randomly within the plant tissue and
exists in various forms or shapes:
brachysclereid
osteosclereid
trichosclerid
macrosclereid
astrosclereid
- a gritty texture that
occurs in pears is due to
the presence of sclereids
- sclereids are sometimes
Sclereids in pear
found in leaves and in
seed coat (particularly
the testa)
Sclereids in bean seed coat
Various forms of sclereids
a. Brachysclereid (sel batu)
d. Astrosclereid
b. Macrosclereid
e. Trichosclereid
c. Osteosclereid
Sclereids
Sclerieds (stone cells) in
fruit tissue of pear
Sclerieds in cross section
of a water lily leaf
Fibres
- often found among
other tissues of plant
organs
- the shape is more
elongated than wide
- the cavity in the
middle of the cell is
termed lumen
- economic importance
of fibres : for making
ropes, canvas etc.