Vascular cambium formed the xylum and pholem. It contained meristematic cell which have continueous growing activity.

1. • Vascular Cambium
• Origin, Structure, Storied and Non-Storied Cell
Types, Additive , Multiplicative
Division…abnormal Secondary Growth
• Class Teacher
Dr. Riffat Siddique
Assistant Professor (BPS-19)
Department of Botany
Lahore College for Women
University, Lahore, Pakistan
• Course Description
Course Title: PLANT ANATOMY
Course code: Maj/Bot-306
Credit hours: 4 (3+1)
• Class
Course : BS III, 6th Semester
Major: Botany s

2. Vascular Cambium
 The vascular cambium is the main growth layer in the
stems and roots.
 Specifically in dicots such as buttercups and oak trees,
and gymnosperms such as pine trees.
 It produces xylem on the inside and phloem on the
outside.
 In herbaceous plants, it occurs in the vascular bundles.
 In woody plants, it forms a continuous ring and grows
new wood on the inside.

3. Origin of Cambium
 The primary vascular tissue is formed by the maturation
of the cells of the procambium strands.
 In plants where secondary growth is absent all the cells
of the procambium strand mature and develop into
vascular tissues.
 Not all the cells of the procambium strand mature into
vascular tissues rather some tissues remain meristematic
Arrange itself between the xylem and phloem of primary
nature.

4. Types of Vascular Cambium
 Intra Fascicular Cambium:
The cambium that arises within the bundles of primary
vascular tissue of the stem is known as intra fascicular
cambium.
 Inter Fascicular Cambium:
The strip of intra fascicular cambium generally
becomes jointed by additional strips of cambium
which are called Inter fascicular cambium.

5. Types of Vascular Cambium
Source:
https://www.google.com/se
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6. Organization of Vascular Cambium
 The cells of vascular cambium are different
from the general meristematic cells.
 The cambial cells are vacuolated.
 The resting cells have less of vacuoles but the
active cambial cells are highly vacuolated.
 The cambial cells are of two kinds ray initial
and fusiform initial:

7. Kinds of cambial cells
 Ray Initials:
These are much smaller than fusiform initials, slightly
elongated and nearly isodiametric in shape. They produce
radial system of the cambial zone.
 Fusiform Initials:
The term fusiform implies that the cell is shaped like a
spindle. A fusiform initial, however, is a prismatic cell in its
middle and wedge shaped at the ends.

8. Ray and Fusiform Initials
Source:
http://www.bio
logydiscussion.
com/stems-
2/dicot-
stem/secondar
y-growth-in-
dicot-stem-
with-
diagram/70397

9. Vascular Cambium Types
 Storied or Stratified Cambium:
 In this case the fusiform initials are shorter and
are arranged in horizontal rows.
 This kind of cambium is found in Tamarix and
Robinia etc.
 According to Bailey the storied cambium have
evolved by gradual reduction of the size of the
cells and by longitudinal sliding growth.

10.  Non-Storied or Non- Stratified Cambium:
 In this case the fusiform initial are longer,
partially overlap one another.
 They are not arranged in horizontal rows.
 This kind of cambium occurs more commonly
in plants.

11. Storied and Non-storied cambium
Source:
https://sl
ideplaye
r.com/sli
de/5275
295/

12. Structure and functions:
 The intrafascicular and interfascicular
cambium join up to form a ring.
 Separates the primary xylem and primary
phloem, the cambium ring.
 The vascular cambium produces secondary
xylem on the inside of the ring, and secondary
phloem on the outside.
 Pushing the primary xylem and phloem apart.

13. Maintenance of cambial meristem:
 The vascular cambium is maintained by a
network of interacting signal feedback loops.
 Currently, both hormones and short peptides
have been identified.
 Similar regulation occurs in other meristems of
plants.
 The cambial meristem receives signals from
both the xylem and phloem sides for the
meristem.

14. Hormonal regulation:
 The hormones that are involved in the vascular
cambial activity are auxins, ethylene,
gibberellins, cytokinins, abscisic acid and more
to be discovered.
 Each one of these plant hormones are vital for
the regulation of the cambial activity and are
dependent on their concentration.

15. Hormonal regulation:
 Auxin:
 This hormone is proven to stimulate mitoses, cell production and
regulate interfascicular and fascicular cambium.
 Applying auxin to the surface of a tree stump allowed shoots to
continue secondary growth.
 The absence of auxin hormones will have a great effect on a plant.
Reduced growth of the vascular bundles.
 Auxin also regulates the two types of cell in the vascular cambium,
ray and fusiform initials. Regulation of these initials ensures the
connection and communication between xylem and phloem is
maintained for the translocation of nourishment and sugars are
safely being stored as an energy resource.

16. Hormonal regulation:
 Gibberline:
 Stimulates the cambial cell division.
 Regulates differentiation of the xylem tissues, with no effect on
the rate of phloem differentiation. Differentiation is an
essential process that changes these tissues into a more
specialized type, playing an important role in maintaining life
form of plant.

17. Hormonal regulation:
 Cytokinin:
 This hormone is known to regulate the rate of the cell
division.
 A study demonstrated that the mutants are found to have a
reduction in stem and root growth but the secondary
vascular pattern of the vascular bundles were not affected
with a treatment of cytokinin.

18. Cell Division in Vascular
Cambium:
 When, the cambial initials produce secondary xylem and
phloem, the divide periclinally.
 At one time a derivative cell is formed towards the xylem, at
another time towards the phloem.
 It’s not necessarily in alternation.
 Each cambial initial forms radial files of cells one towards the
outside and the other towards inside and the two files meet at
the cambial initial.

19.  With the increase in thickness of core of secondary xylem, the
cambium is displaced outwardly.
 Circumference enhances.
 The increase is accomplished by divisions of cells.
 The phenomenon is called dilation. New ray cells are also added.
They form additional rays every year. The vascular cambium
undergoes two types of divisions— additive (periclinal divisions for
formation of secondary tissues) and multiplicative (anticlinal
divisions for dilation).
 Ray initials produce radial system (= horizontal or transverse
system) while fusiform initials form axial system (= vertical
system) of secondary vascular tissues.

20. Cell Division in Cambium
 Source:http://www-
plb.ucdavis.edu/labs/rost/Tomato/S
tems/secstem3.html
https://slideplayer.com/slide/107
52669/

21. Seasonal Activity of Vascular
Cambium:
 In plants growing in tropical regions, cambium is active
throughout the whole life of plants.
 In contrast to this, in plants of temperate region, the cambium
almost ceases its activity with the commencement of
unfavourable season.
 generally in autumn and this dormant stage remains till the
following spring when it is reactivated and produces new
xylem and phloem.
 The cambial cells take up water, enlarge radially and divide
periclinally.

22. The Vascular Cambium and
Secondary Growth:
 The vascular cambium and cork cambium are secondary
meristems formed in stems and roots.
 After the tissues of the primary plant body have
differentiated.
 The vascular cambium is responsible for increasing the
diameter of stems and roots and for forming woody
tissue.
 The cork cambium produces some of the bark.

24. The Vascular Cambium and
Secondary Growth
 In dicot stems, the vascular cambium initially
differentiates from procambial cells within the vascular
bundles.
 Monocots do not have a vascular cambium, some of
them, such as palms and the Joshua tree, exhibit
secondary growth.
 They have a thickening meristem that produces
secondary ground tissue.
 Increases the girth of the stem and additional vascular
bundles differentiate within the secondary ground tissue.

25. Anomalous Secondary Growth:
 It is abnormal type of secondary growth that occurs in some arborescent
monocots (e.g., Dracaena, Yucca, Agave) and storage roots (e.g., Beet,
Sweet Potato). In arborescent monocot stems, a secondary cambium
grows in hypodermal region. The latter forms conjunctive tissue and
patches of meristematic cells. The meristematic patches grow into sec-
ondary vascular bundles.
 Anomalous vascular bundles also occur in cortex (cortical bundles, e.g.,
Nyctanthes) and pith (e.g., Boerhaavia). In storage roots (e.g., Beet),
accessory cambial rings appear on the outside of endodermis. They
produce less secondary xylem but more secondary phloem. The
secondary phloem contains abundant storage parenchyma.
 http://www.biologydiscussion.com/stems-2/dicot-
stem/secondary-growth-in-dicot-stem-with-diagram/70397

26. Importance of Secondary
Growth:
 1. It is a means of replacement of old non-functional tissues with
new active tissues.
 2. The plants showing secondary growth can grow and live longer
as compared to other plants.
 3. It provides a fire proof, insect proof and insulating cover around
the older plant parts.
 4. Commercial cork is a product of secondary growth. It is obtained
from Quercussuber (Cork Oak).
 5. Wood is a very important product of secondary growth. It
represents secondary xylem.