This document discusses the three types of meristematic tissues in plants: apical meristems, intercalary meristems, and lateral meristems. Apical meristems are located at shoot and root tips and facilitate primary growth. Dicots have apical meristems in both shoots and roots, while monocots only have them in roots. Monocots also have intercalary meristems that allow leaf regrowth. Lateral meristems cause secondary growth in dicots by increasing stem diameter. The document also describes simple and complex permanent tissues, including parenchyma, collenchyma, sclerenchyma, xylem, and phloem.

4. Meristematic Tissues
 Meristems are places in plants where cell division is
occurring.
 During cell division, one cell becomes two cells. Each
new cell can also divide.

5. Meristematic Tissues
 In this class we will discuss three kinds of meristems:
 Apical Meristems
 Intercalary Meristems
 Lateral Meristems

6. Apical Meristems
 In plants belonging to
the DICOT class,
apical meristems are
located in BOTH the
shoot tips and root
tips. A shoot is simply
a young, leaf-bearing
stem.
 In plants belonging to
the MONOCOT class,
apical meristems are
located ONLY in the
root tips.
Microscopic View of an Apical
Meristem

7. Apical Meristems
•Primary growth of shoots
and roots occurs as the cells
of the apical meristem
divide and elongate.

8. Intercalary Meristems
 In addition to the apical meristems located in their
root tips, plants in the MONOCOT class have special
meristems called intercalary meristems.
 Intercalary meristems are located on monocots where
the leaf bases connect to the stem of the plant.

9. Intercalary Meristems
Monocots, like grasses, have intercalary meristems which
allow the leaves to grow back after mowing.

10. Lateral Meristems
 In addition to the
apical meristems
located in the shoot
and root tips, plants in
the DICOT class have
lateral meristems.
 Lateral meristems
cause SECONDARY
GROWTH.
 Secondary growth
causes stems and roots
to grow larger in
diameter.
Lateral Meristems cause an increase
in stem diameter

11. Lateral Meristems
Think of a lateral
meristem as being a
cylinder, several cell
layers thick, of actively
dividing cells.

12. Permanent Tissues
Permanent tissues are of two types;
Simple permanent tissue
Complex permanent tissue

14. Simple permanent tissue
 Parenchyma
 store food and water
 Collenchyma
 provide support for plant organs
 Sclerenchyma
 supporting function
 secondary walls impregnated with lignin
 fibers and sclerids
 may be nonliving at maturity

15. Parenchyma
- are the general purpose ceIIs of plants - cells are
rounded in shape & have uniformly thin walls
found in all parts of the plants.
- living at maturity, have large vacuoles
- location Ieaf, stem (pith), roots, fruits

16. collenchyma
 cells are elongated (up to 2mm long) with unevenly
thickened walls ( thin on the sides but thick at the
angles where 2 or more cells meet)
 differentiate from parenchyma cells & are alive at
maturity

17. sclerenchyma
 - sclerenchyma cells which are non-living and lack
protoplasts at maturity
Types:
1. scIereids or stone cells
2. fibers

18. Complex Permanent Tissues
Vascular Tissues
- specialized for long-distance transport of water
and dissolved substances.
- contain transfer ceIIs, fibers in addition to
parenchyma and conducting ceIIs
- location, the veins in Ieaves
 types
1. Xylem
2. phloem

19. Xylem
 Xylem tissue conducts
water and dissolved
mineral nutrients.
 It is composed of columns
of vessel cells (tracheids in
gymnosperms), stacked
one upon another, and
fibers.
 Vessel cell walls are pitted
and allow water passage
between the xylem and
surrounding tissues.
Mature xylem cells are
dead.
Xylem Phloem

20.  Xylary elements – the conducting cells in xylem
- 2 kinds of xylary elements:
 tracheids – the only water conducting cells
in most woody, non flowering plants.
 vessel elements – occur in several groups of
plants, including angiosperm.
- both are elongated, dead at maturity, lignified secondary cell
walls

21. Phloem
 Phloem tissue conducts the
food produced by the leaves
in a downwards direction to
stems and roots (from source
to sink).
 Phloem is composed of sieve
tubes, companion cells, and
fibers.
 The end walls of the sieve
tubes are called sieve plates.
Xylem Phloem

22. Sieve tube elements – main conducting ceIIs
of phloem
- elongated and non-nucleated
- uniformly thin walled with the end walls
perforated to from the sieve plate.
- sieve tube element are attached end to end
to form the sieve tube.