1. VASCULAR AND MECHANICAL
Lecture 3
VASCULAR AND MECHANICAL
TISSUES OF PLANTS.
VASCULAR BUNDLES
Author: ass.-prof.
Shanayda M.I.

2. At the last lecture were stadied different types of plant
tissues – the meristem, dermal, secretory and ground.
At present we are studying the VASCULAR
and MECHANICAL tissues of plants.
VASCULAR and MECHANICAL
tissues of plants
contain 90 % of wood in trees

5. MECHANICAL
TISSUES
The tissues that support plant are called mechanical tissues. Their cells have thickening of walls in different directions.
They belong to simple tissues, because include only one type of cells.
There are two types of mechanical tissues…

7. Collenchyma tissues are mainly found under the epidermis in young stems and in the large veins of leaves. The cells are composed of living, elongated cells. Collenchyma cells have thick cellulose cell walls. The cells sometimes contain chloroplasts.

8. Types of collenchyma are classified according to the arrangement of the cell wall thickenings and include:
angular collenchyma: cell wall is thickest in the corners (in herbal parts of plants).
lamellar collenchyma: cell wall is thickest on two opposite sides (in the bark)
lacunar collenchyma:
cell wall is thickest in the corners, intercellular air
(in water plants)

9. 1) fibers are long, straight and thin,
Sclerenchyma tissues have the rigid thick secondary cell walls with lignin.
They support nonextending regions of plants such as mature stems, and are usually dead. Sclerenchyma also makes up the hard outer covering of seeds and nuts. Cell walls are usually lignified.
Types of sclerenchyma are classified
according to cell shape and include
fibers and sclereids
1) fibers are long, straight and thin,
often occurring in vascular bundles.
Usually fiber cells are much longer than
they are wide and have a very tiny cavity
in the center of the cell.

10. 2) Sclereids are variable in shape, but not like fibers
2) Sclereids are variable in shape, but not like fibers. Types are classified according to shape and include the following:
brachysclereids: also called stone cells, their length and width are nearly equal.
astrosclereids: star shaped, with several projecting arms. trichosclereids: hair-like, similar to a fibers, except branched. osteosclereids: bone shaped, elongated with swollen ends.
macrosclereids: column shaped

11. Groups of
brachysclereids (3,4)
on cross section
of the oak-tree bark

12. The VASCULAR
TISSUES
The VASCULAR TISSUES are specialized for long-distance.
Xylem and phloem are two the most important complex tissues in a plant, as their primary functions include the transport of water, dissolved minerals and soluble food substances (photosynthate) throughout the plant.

13. Xylem and phloem

14. Vessel elements are the long
XYLEM conducts water and dissolved minerals from the roots to all the other parts of the plant (xylem is the water-conducting tissue of plants).
Xylem is a complex tissue composed of xylem vessels (or tracheids), fibers and parenchyma cells:
Vessel elements are the long
tube with perforation plates.
Xylem vessels of Angiosperm
are deposited in
spirals and rings and are
usually perforated by pits.

15. Tracheids are the conducting elements
that lack perforations plates (there are pits).
The xylem of Conifers contains only tracheids.

16. 3) Xylem parenchyma cells
2) Libriform fibers are the cells
of mechanical tissue in the xylem.
They are very long and dead.
Their functions are
to serve as supporting
elements of xylem.
3) Xylem parenchyma cells
are alive and have thin wall.
They distinct
the intercellular spaces.
SUMMARY …

17. PHLOEM is the photosynthate-conducting tissue of plants.
Phloem is a complex tissue composed of sieve elements, companion cells, long fiber elements and parenchyma cells. The main components of phloem are sieve elements and companion cells.

18. and without secondary wall.
Sieve elements are the
conducting cells in the phloem.
They are with perforation plates
and without secondary wall.
Sieve elements have no nucleus and
depend on the adjacent companion cells
for many functions.
Companion cells are cells
in the phloem that is connected
to a sieve-tube member by
numerous plasmodesmata.
They have a nuclei.
The phloem of Conifers
has no companion cells.
SUMMARY …

19. The VASCULAR BUNDLES
The xylem and phloem are the two most important complex tissues
in a plant and situated in organs of plants together as vascular bundles.
Sometimes they contain a vascular cambium (the lateral meristem).

20. The VASCULAR BUNDLES are classified according to special relationships of xylem and phloem. There are several types of vascular bundles. All these types are typical for some taxonomical categories (divisions, classes, families) and different plant organs:

21. KINGDOM OF PLANTS Division of Angiosperm Dicotyledonous class
Green algae
The Poppy Family
The Grass Family
Monocotyledonous class
Division of Angiosperm
Division of...
Division of...
Division of...
Division of...

22. Collateral bundles have xylem on one side and phloem on the other side
Collateral bundles have xylem on one side and phloem on the other side. There are close and open collateral bundles: opened collateral vascular bundle (with cambium) formed in stems of Dicotyledon plants (1);
closed collateral vascular bundle (without cambium) formed in stems and leaves of Monocotyledon plants (3);
Bicollateral bundles have phloem on both sides of the xylem; they also have cambium (formed in stems of pumpkin (2),

23. Concentric bundles are common only for rhizomes
(underground shoot modifications). They are divide to:
Centerphloem amphivasal – if xylem surrounds
the phloem (in Monocots – (4), Centerxylem amphicribral – if phloem surrounds
the xylem (in Ferns – (5)

24. Radial bundles have xylem occurs in radial directions, and
phloem takes place between them
(in young roots with primary structurae). Radial
polyarch vascular bundle is typical only for roots of Monocot
plants. Dicot have radial tetraarch or tryarch vascular bundle.

25. GLOSSARY OF TISSUES OF THE PLANT BODY

29. 1. MERISTEMS produce all types of permanent tissues.
There are general zone in which cell dividing is frequent.
2. DERMAL TISSUES cover the surface of the plant
body and protect it. There are alive and
dead complex tissues.
3. GROUND TISSUES SYSTEM are simple
tissues composed of alive cell. They can
accumulate of storage products, air and photosynsate.
4. SECRETORY STRUCTURES produce different
solutions, can be of outer and inner forms.
5. MECHANICAL TISSUES….
6. VASCULAR TISSUES …

30. KROK-1 test questions
The stems microscopically analysis revealed complex tissue that
consists of sieve tubes with companion cells, fibers and parenchyma.
This is...
A periderm
B cork
C xylem
D phloem
E epidermis
The investigation found that rising transport of dissolved minerals is
provide by...
A Sieve elements
B. Vessels and tracheids
C Libriform fibers
D. Angular collenchyma
E. Fiber phloem elements
What type of vascular bundle is typical for the primary structure of root?
A Radial
B Concentric
C Сollateral closed
D Bikollateral
E Сollateral open