The vascular cambium is a lateral meristem that increases the diameter of stems and roots through secondary growth. It is composed of fusiform initials that divide to form vertical tissues and ray initials that form horizontal tissues. In dicots, intrafascicular cambium initially develops within vascular bundles and interfascicular cambium develops between bundles, eventually joining to form a complete cambial ring. The cambium divides to produce secondary xylem internally and secondary phloem externally. Its seasonal activity varies the structure of the tissues produced.
Vascular Cambium & Seasonal activity & its Role in Stem & RootFatima Ramay
Vascular Cambium & Seasonal activity & its Role in Stem & Root:
The vascular cambium (pl. cambia or cambiums) is a lateral meristem in the vascular tissue of plants.
The vascular cambium is a cylindrical layer of cambium that runs through the stem of a plant that undergoes secondary growth.
In Dicots:
The vascular cambium is in dicot stems and roots, located between the xylem and the phloem in the stem and root of a vascular plant, and is the source of both the secondary xylem growth (inwards, towards the pith) and the secondary phloem growth (outwards).
In Monocots:
Monocot stems, such as corn, palms and bamboos, do not have a vascular cambium and do not exhibit secondary growth by the production of concentric annual rings. They cannot increase in girth by adding lateral layers of cells as in conifers and woody dicots.
Cambium of some plants remains active for the entire period of their life, i.e., cambial cells divide and resulting cells mature to form xylem and phloem elements.
This type of seasonal activity usually found in the plants present in the tropical regions, and not all plants show cambial activity.
Percentage of ringless trees in the rain forests of; India : 75% Amazon : 43% Malaysia : 15%
In regions with definite seasonal climate; seasonal activity of cambium ceased with onset of unfavorable conditions; In Autumn, it enters the dormant state and lasts for the end of summer; In Spring, cambium again becomes active.
Duration of cambial activity is also affected by day-length, e.g., In Robinia pseudoacacia, cambium is dormant under short-day condition.
The cambium cells formed in circular in cross section from the beginning onwards.
The cambial ring is partially primary (fascicular cambium) and partially secondary (interfascicular cambium).
Periderm originates from the cortical cells (extra stelar in origin).
In Dicot stem, for mechanical support xylem is with comparatively smaller vessels, greater fibers and less parenchyma.
More amount of cork is produces for protection.
Lenticels on periderm are very prominent.
The cambial ring formed is wavy in the beginning and later becomes circular.
The cambium ring is completely secondary in origin.
Periderm originates from the pericycle (intra stelar in origin).
In Dicot root, xylem is with big thin walled vessels with few fibers and more parenchyma.
Less amount of cork is produced as root is underground.
Lenticels on periderm are not very prominent.
The Shoot apex is also known as the terminal bud of plants that grows from 0.1-1.0 mm and consists of the apical meristem, developing leaves and the immediate surrounding leaf primordial. The shoot apex is present in both dicot and monocot plants.
The timing of cambial reactivation plays an important role in determination of the amount and quality of wood and the environmental adaptavity of trees.
Environmental factors, such as temperatures, influence the growth and development of trees.
Temperatures from late winter to early spring affect the physiological process that are involved in the initiation of cambial cell division and xylem differentiation in trees.
Cumulative elevated temperatures from late winter to early spring result in earlier initiation of cambial reactivation and xylem differentiation in tree stems and an extended growth period.
However, earlier cambial reactivation increases the risk for frost damage because the cold tolerance of cambium decreases after cambial reactivation.
A better understanding of the mechanisms that regulate wood formation in trees and the influence of environmental conditions on such mechanisms should help in efforts to improve and enhance the exploitation of wood for commercial applications and to prepare for climatic change.
Wood is the product of vascular cambium, and the formation of wood depends on the cambial activity of trees.
In temperate and cool zones, the vascular cambium of the stems of trees undergoes seasonal cycles of activity and dormancy, which are collectively known as annual periodicity.
This periodicity plays an important role in the formation of wood and reflects the environmental adaptivity of trees, for example their tolerance to cold in winter in cool and temperate zones.
The quantity and quality of wood depend on the division of cambial cells and the differentiation of cambial derivatives.
Cambial activity in trees is regulated by both internal factors, such as plant hormones, and environmental factors, such as, temperature, rainfall and photoperiod.
Temperature provides the appropriate physical conditions for the growth and development of trees in temperate and cool climates.
Timing of cambial reactivation is controlled by temperature, which influences both the quantity and quality of wood.
During the period from late winter to early spring, new cell plates are formed in the cambium and this springtime phenomenon is referred to as cambial reactivation.
Vascular Cambium & Seasonal activity & its Role in Stem & RootFatima Ramay
Vascular Cambium & Seasonal activity & its Role in Stem & Root:
The vascular cambium (pl. cambia or cambiums) is a lateral meristem in the vascular tissue of plants.
The vascular cambium is a cylindrical layer of cambium that runs through the stem of a plant that undergoes secondary growth.
In Dicots:
The vascular cambium is in dicot stems and roots, located between the xylem and the phloem in the stem and root of a vascular plant, and is the source of both the secondary xylem growth (inwards, towards the pith) and the secondary phloem growth (outwards).
In Monocots:
Monocot stems, such as corn, palms and bamboos, do not have a vascular cambium and do not exhibit secondary growth by the production of concentric annual rings. They cannot increase in girth by adding lateral layers of cells as in conifers and woody dicots.
Cambium of some plants remains active for the entire period of their life, i.e., cambial cells divide and resulting cells mature to form xylem and phloem elements.
This type of seasonal activity usually found in the plants present in the tropical regions, and not all plants show cambial activity.
Percentage of ringless trees in the rain forests of; India : 75% Amazon : 43% Malaysia : 15%
In regions with definite seasonal climate; seasonal activity of cambium ceased with onset of unfavorable conditions; In Autumn, it enters the dormant state and lasts for the end of summer; In Spring, cambium again becomes active.
Duration of cambial activity is also affected by day-length, e.g., In Robinia pseudoacacia, cambium is dormant under short-day condition.
The cambium cells formed in circular in cross section from the beginning onwards.
The cambial ring is partially primary (fascicular cambium) and partially secondary (interfascicular cambium).
Periderm originates from the cortical cells (extra stelar in origin).
In Dicot stem, for mechanical support xylem is with comparatively smaller vessels, greater fibers and less parenchyma.
More amount of cork is produces for protection.
Lenticels on periderm are very prominent.
The cambial ring formed is wavy in the beginning and later becomes circular.
The cambium ring is completely secondary in origin.
Periderm originates from the pericycle (intra stelar in origin).
In Dicot root, xylem is with big thin walled vessels with few fibers and more parenchyma.
Less amount of cork is produced as root is underground.
Lenticels on periderm are not very prominent.
The Shoot apex is also known as the terminal bud of plants that grows from 0.1-1.0 mm and consists of the apical meristem, developing leaves and the immediate surrounding leaf primordial. The shoot apex is present in both dicot and monocot plants.
The timing of cambial reactivation plays an important role in determination of the amount and quality of wood and the environmental adaptavity of trees.
Environmental factors, such as temperatures, influence the growth and development of trees.
Temperatures from late winter to early spring affect the physiological process that are involved in the initiation of cambial cell division and xylem differentiation in trees.
Cumulative elevated temperatures from late winter to early spring result in earlier initiation of cambial reactivation and xylem differentiation in tree stems and an extended growth period.
However, earlier cambial reactivation increases the risk for frost damage because the cold tolerance of cambium decreases after cambial reactivation.
A better understanding of the mechanisms that regulate wood formation in trees and the influence of environmental conditions on such mechanisms should help in efforts to improve and enhance the exploitation of wood for commercial applications and to prepare for climatic change.
Wood is the product of vascular cambium, and the formation of wood depends on the cambial activity of trees.
In temperate and cool zones, the vascular cambium of the stems of trees undergoes seasonal cycles of activity and dormancy, which are collectively known as annual periodicity.
This periodicity plays an important role in the formation of wood and reflects the environmental adaptivity of trees, for example their tolerance to cold in winter in cool and temperate zones.
The quantity and quality of wood depend on the division of cambial cells and the differentiation of cambial derivatives.
Cambial activity in trees is regulated by both internal factors, such as plant hormones, and environmental factors, such as, temperature, rainfall and photoperiod.
Temperature provides the appropriate physical conditions for the growth and development of trees in temperate and cool climates.
Timing of cambial reactivation is controlled by temperature, which influences both the quantity and quality of wood.
During the period from late winter to early spring, new cell plates are formed in the cambium and this springtime phenomenon is referred to as cambial reactivation.
Short, sweet, and presentable details of the following basic types of vascular bundle.
Collateral
Bicollateral
Open: the presence of cambium
Concentric
Radial: on the different radius
with diagram
Alternative type of cambium show abnormal activity and produce alternative secondary bodies that differ from common type, their growth is called anomalous secondary growth.
There is two types of anomalous secondary
Growth;
Abnormal growth from normal cambium in dicot
Abnormal growth from abnormal cambium in monocot
Ginkgo is known as a Living Fossil.Anatomy of Ginkgo clearly shows primary and secondary structures. sex in Ginkgo is determined by sex chromosomes (XY in male and XX in female). Reproductive bodies of Ginkgo are most primitive among living seed plants except some Cycadales. Ginkgos are dioecious, with separate sexes, some trees being female and others being male. Male plants produce small pollen cones with sporophylls, each bearing two microsporangia spirally arranged around a central axis. Female plants do not produce cones. Two ovules are formed at the end of a stalk, and after pollination, one or both develop into seeds. The fertilization of ginkgo seeds occurs via motile sperm, as in cycads, ferns, mosses and algae.
Short, sweet, and presentable details of the following basic types of vascular bundle.
Collateral
Bicollateral
Open: the presence of cambium
Concentric
Radial: on the different radius
with diagram
Alternative type of cambium show abnormal activity and produce alternative secondary bodies that differ from common type, their growth is called anomalous secondary growth.
There is two types of anomalous secondary
Growth;
Abnormal growth from normal cambium in dicot
Abnormal growth from abnormal cambium in monocot
Ginkgo is known as a Living Fossil.Anatomy of Ginkgo clearly shows primary and secondary structures. sex in Ginkgo is determined by sex chromosomes (XY in male and XX in female). Reproductive bodies of Ginkgo are most primitive among living seed plants except some Cycadales. Ginkgos are dioecious, with separate sexes, some trees being female and others being male. Male plants produce small pollen cones with sporophylls, each bearing two microsporangia spirally arranged around a central axis. Female plants do not produce cones. Two ovules are formed at the end of a stalk, and after pollination, one or both develop into seeds. The fertilization of ginkgo seeds occurs via motile sperm, as in cycads, ferns, mosses and algae.
CAMBIUM GROWTH, SECONDARY GROWTH I STEM AND ROOTS, ANNUAL RINGS, WHY NOT IN MONOCOTS, CHANGES BEFORE AND AFTER GROWTH (*SOME SLIDES HAVE CUSTOM ANIMATION EFFECTS)
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2. VASCULAR CAMBIUM
• Introduction
# In majority of monocotyledons and pteridophytes the primary plant body
structurally and functionally complete. In most dicotyledons and
gymnosperms,primary growth is soon followed by secondary growth.
# Secondary growth take place by the activity of cambium
# The vascular cambium Is a lateral meristem. It is a continuous sheath of the
meristematics cells. The vascular cambium increase the diameter or girth of plant by
secondary growth .
#Cambium divide and produce the new cells toward the inner as well as outer side.
# In dicot stem the first procambium that develops from promeristem present in the
form of patches in each vascular bundle between the primary phloem and primary
xylem called intrafascicular cambium or fascicular cambium.
# The new cambium develop from the interfascicular region, some parenchymatous
cells become meristematic and forme the secondary cambium which present
between the two vascular bundles called interfascicular cambium .
# The fascicular and interfascicular cambium joined together and form a complete
ring of cambium cells known as cambial ring.
3.
4. Structure of cambium
• The vascular cambium is made up of the two components-
1-Fusiform initial and 2- Ray initial
1- Fusiform initial- These cells are spindle shaped and long with
their pointed ends. It divide to form all cells of vertical system. The
arrangement of the fusiforn initial is mainly two types in different
plants. 1- stratified arrangements and 2-non stratified
arrangement.
# Stratified arrangement:When the fusiform initial cells arrange
horizontally in the same level , it is called stratified arrangement. Eg.
Dalbergia sisso. and the cambium is called stratified cambium.
# Non stratified arrangement: When the fusiform initial are not
arranged regularly in horizontally row it is called Non stratified
arrangement,and the cambium is called non stratified cambium.
5. 2. Ray initial –The ray initial cells are Smaller than the fusiform initial
with their flattened axis.The ray initials are isodiametric cells—about
equal in all dimensions—and they produce the vascular rays, which
constitute the horizontal system of secondary tissues; this horizontal
system acts in the translocation and storage of food and water.
6.
7. Function of cambium
• The main function of cambium is the increasing the girth of the plant
i.e. The secondary growth of the complex permanent tissues (xylem
and phloem) the cambium divide tangential division and add new cells
toward both side. The cambium forms the cells outside differentiate
into secondary phloem and which produce toward inner side are
differentiate into secondary xylem. The ray initial gives rise to xylem
and phloem rays.
• During the division of cambium it gives an appearance of
multilayered cambium known as cambial zone, but actually the
cambium remain single layered.
8.
9. Seasonal activity of cambium
• Cambium of some plants remain active for their entire life time i.e cambial
cell divides and resulting cells mature to form xylem and phloem element.
• Not the all plant show the cambial activity. The seasonal activity usually
found in the plants of the tropical region.
• In autmn season cambium enters in dormant state and last for the end of
summer. In spring season cambium again become active.
• In autmn season (unfavorable) cambium is less active and produce the
thick walled narrow, dark brown and much smaller xylem tissue(vessels are
narrow)
• In spring season (favorable) cambium become more active and produse
large size, thin walled and light color xylem element (vessels are large)
which conduct more water than those produce in unfavorable conditions.
10.
11. Multiple choice questions
• Q:1 In dicot stem the cells of horizontal system produced from-
• (a) fusiform initial (b) cork cambium
• (c) Fascicular cambium (d) ray initial
• Q:2 Vascular cambium is-
• (a) apical meristem (b) lateral meristem
• (c) intercalary meristem (d) none of these
• Q:3 Intra-fascicular cambium present in-
• (a) between the xylem and phloem (b) between the two different vascular bundles
• (c) outside the xylem (d) in cortex
• Q:4 Which type of vascular tissue produced just outside the vascular cambium-
• (a) xylem (b) phloem
• (c) heartwood (d) parenchyma
• Q:5 Xylem tissue is responsible to transporting of what substance?
• (a) starch (b) sugar molecules
• (c) water and minerals (d) chlorophyll
12. • Ans:1 - (d) ray initial
• Ans:2 - (b) lateral meristem
• Ans:3 - (a) between xylem and phloem
• Ans:4 - (b) phloem
• Ans:5 - (c) water and nutrients
13. • Q:6 If four radial vascular bundle are present the structure will be-
• (a) monocot stem (b) monocot root
• (c) dicot root (d) dicot stem
• Q:7 Fascicular cambium present in dicot stem is-
• (a) Intercalary meristem (b) primary meristem
• (c) secondary meristem (d) apical meristem
• Q:8 Which one of the tissue formed in stems from cells cut off by the cambium on its inner side-
• (a) bast fibres (b) wood fibres
• (c) phalloderm (d) sieve tubes
• Q:9 Vascular cambium and cork cambium are-
• (a) part of secondary xylem and secondary phloem (b) part of epidermis
• (c) lateral meristem (d) intercalary meristem
• Q:10 In dicot stem the secondary growth take place by-
• (a) primary cambium (b) secondary cambium
• (c) development of cambium in stele region (d) development of cambium in stele and in
• cortical region
14. • Ans :6 -(d) dicot root
• Ans :7 -(b) primary meristem
• Ans :8 -(b) wood fibres
• Ans :9 -(c) lateral meristem
• Ans :10 -(d) development of cambium in stele and cortical region
