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 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.
Wall layers of anther have different functions most importantly they help in providing nutrition to developing pollens and also help in anther dehiscence.
Pteridophytes are vascular plants and have leaves (known as fronds), roots and sometimes true stems, and tree ferns have full trunks. Examples include ferns, horsetails and club-mosses. Fronds in the largest species of ferns can reach some six metres in length!
Many ferns from tropical rain forests are epiphytes, which means they only grow on other plant species; their water comes from the damp air or from rainfall running down branches and tree trunks. There are also some purely aquatic ferns such as water fern or water velvet (Salvinia molesta) and mosquito ferns (Azolla species).
Pteridophytes do not have seeds or flowers either, instead they also reproduce via spores.
There are around 13,000 species of Pteridophytes.
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.
Angiosperm Phylogeny Group classification
APG I
APG II
APG III
APG IV
Molecular Based system
features and organization
Merits and demerits
Difference in APG system.
The "Telome theory" of Walter Zimmermann (1930, 1952) is the most accepted theory that is based on fossil record and synthesizes the major steps in the evolution of vascular plants.
It describes how the primitive type of vascular plants developed from Rhynia like plants.
What is Meristematic Tissue? Carl Wilhelm von Nägeli coined the term “meristem.” Meristematic tissue contains undifferentiated cells, which are the building blocks of the specialized plant structures. Meristematic tissues contain living cells with varied shapes.
Wall layers of anther have different functions most importantly they help in providing nutrition to developing pollens and also help in anther dehiscence.
Pteridophytes are vascular plants and have leaves (known as fronds), roots and sometimes true stems, and tree ferns have full trunks. Examples include ferns, horsetails and club-mosses. Fronds in the largest species of ferns can reach some six metres in length!
Many ferns from tropical rain forests are epiphytes, which means they only grow on other plant species; their water comes from the damp air or from rainfall running down branches and tree trunks. There are also some purely aquatic ferns such as water fern or water velvet (Salvinia molesta) and mosquito ferns (Azolla species).
Pteridophytes do not have seeds or flowers either, instead they also reproduce via spores.
There are around 13,000 species of Pteridophytes.
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.
Angiosperm Phylogeny Group classification
APG I
APG II
APG III
APG IV
Molecular Based system
features and organization
Merits and demerits
Difference in APG system.
The "Telome theory" of Walter Zimmermann (1930, 1952) is the most accepted theory that is based on fossil record and synthesizes the major steps in the evolution of vascular plants.
It describes how the primitive type of vascular plants developed from Rhynia like plants.
What is Meristematic Tissue? Carl Wilhelm von Nägeli coined the term “meristem.” Meristematic tissue contains undifferentiated cells, which are the building blocks of the specialized plant structures. Meristematic tissues contain living cells with varied shapes.
A cell is the structural and fundamental unit of life.
The study of cells from their basic structure to the functions of every cell organelle is called Cell Biology.
Robert Hooke was the first Biologist who discovered cells.
All organisms are made up of cells. They may be made up of a single cell (unicellular), or many cells (multicellular).
Mycoplasmas are the smallest known cells.
Cells are the building blocks of all living beings. They provide structure to the body and convert the nutrients taken from the food into energy.
Cells are complex and their components perform various functions in an organism. They are of different shapes and sizes, pretty much like the bricks of the buildings. Our body is made up of cells of different shapes and sizes.
Cells are the lowest level of organisation in every life form. From organism to organism, the count of cells may vary. Humans have more cells compared to that bacteria.
Cells comprise several cell organelles that perform specialised functions to carry out life processes. Every organelle has a specific structure. The hereditary material of the organisms is also present in the cells.
Aim : to study cell and it's organelle with help of electron microscope.
Cells are the basic building blocks of living things. The human body is composed of trillions of cells, all with their own specialised function.
Cells are the basic structures of all living organisms.
Cells provide structure for the body, take in nutrients from food and carry out important functions.
Cells group together to form tissues?, which in turn group together to form organs?, such as the heart and brain.
Our cells contain a number of functional structures called organelles?.
These organelles carry out tasks such as making proteins?, processing chemicals and generating energy for the cell.
The nucleus? is based at the centre of the cell and is the ‘control room’ for the cell.
The genome? is found within the nucleus.
Instructions for Submissions thorugh G- Classroom.pptxJheel Barad
This presentation provides a briefing on how to upload submissions and documents in Google Classroom. It was prepared as part of an orientation for new Sainik School in-service teacher trainees. As a training officer, my goal is to ensure that you are comfortable and proficient with this essential tool for managing assignments and fostering student engagement.
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
How to Split Bills in the Odoo 17 POS ModuleCeline George
Bills have a main role in point of sale procedure. It will help to track sales, handling payments and giving receipts to customers. Bill splitting also has an important role in POS. For example, If some friends come together for dinner and if they want to divide the bill then it is possible by POS bill splitting. This slide will show how to split bills in odoo 17 POS.
The Art Pastor's Guide to Sabbath | Steve ThomasonSteve Thomason
What is the purpose of the Sabbath Law in the Torah. It is interesting to compare how the context of the law shifts from Exodus to Deuteronomy. Who gets to rest, and why?
The Art Pastor's Guide to Sabbath | Steve Thomason
Theory of shoot apical meristem
1. Theories Of Shoot Apical Meristem
Presented by : Panchal Rita C.
M.sc Sem : 2
Roll no. 205
CBO: 405
Department Of life Sciences, H.N.G.U. Patan
2. Content
• Introduction
• Apical cell Theory
• Histogenic layer Theory
• Anneu initial & meristem d'attente Theory
3. Introduction
• The shoot apical meristem is the terminal
meristem of the shoot which is the
continuing embryonic region of the plant.
• It continuously gives rise to new cells and
tissues from which new organs are formed.
• It is self determining and autonomous
organising centre of the plant.
4. • Apical Cell Theory
• Presence of a single tetrahedral apical cell
in the shoot apex of most vascular
Cryptogams prompted Nageli (1878) to
postulate the apical cell theory.
• According to this theory a single apical cell
is the structural and functional unit of
apical meristem and it governs the whole
process of growth.
5. • Such a single apical cell occurs in algae and
majority of bryophytes and pteridophytes.
• A single apical cell was also believed to be
present in seed plants.
6.
7. Histogenic layer Theory
• According to Dermen (1947) the terms
tunica and corpus do not have fixed values
and they fall short of having real meaning
histogenetically.
• He recognized three basic histogenic layers
in all angiospermic Plants which were
referred to as L -1 , L-2 and L-3 layers.
8. • These layers exist in various combinations of
ploidy in the shoot apices.
• For example the cells of L-1 may be 2x, to
those of L- 2-2x and those of L-3-4x.
• Expressed in terms of ploidy the Constitution
would be 2,2,4.
9. • The epidermis of the stem and leaves is
derived from L-1. The L-2 layer forms L-3
layered hypodermic of stems in some
cases inner cortical tissues are also derived
from it and in still others it may contribute
to a portion of vascular tissue.
• In general the vascular tissue and pith
originate from L-3 layer.
10.
11. Anneu Initial and Meristem
d'attente Theory
• Buvat (1955) proposed that peripheral and
subterminal regions are real initiating zones
wheres distal zones are inert in nature.
• He recognised three distinct regions in apical
meristem.
1. The anneu ( the peripheral active zone)
2. The meristem d'attente ( the waiting meristem
which becomes active only during formation of
terminal flower or inflorescence)
12. 3. The meristem medullary ( the central pith region)
• Meristem d'attente consists of two parts the
promeristeme sporogene and promeristeme
receptaculair which thus contain part of tunica
(except anneu Initial) and part of corpus ( except
meristem medullary)
• This Theory becomes Controversial Mainly
because it consides meristem d’attente as waiting
meristem which were priviously regarded as apical
initial.
13.
14. • References
• A Text book of botany plant anatomy and
economic botany volume -3 :
by – S.N.Pandey
A. Chadha
• Text book of Botany Angiosperms by: B.P.Pandey
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