Botany lecture notes

Classification of Gymnosperms PPT (Chamberlain System – 1934)


Plant Science PPT

Classification of Gymnosperms PPT
(Chamberlain System of Classification of Gymnosperms – 1934)

Classification of Gymnosperms, Outline of the history of Classification of Gymnosperms, Chamberlain System of Classification of Gymnosperms, Class Cycadophyt and Coniferophyt, Order Cycadofilicales (Pteridospermales) Cycdeoidales (Bennettitles) and Cycdales, Order Cordaitales, Ginkgoales, Coniferales and Gnetales.

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Botany lecture notes

Classification of Gymnosperms by Chamberlain (1934)


Classification of Gymnosperms

Classification of Gymnosperms
The Chamberlain System – 1934

Brief history of the classification of Gymnosperms:

There are many systems for the classification of Gymnosperms in the literature. Robert Brown (1827) for the first time recognized Gymnosperms as a separate group of plants. Bentham and Hooker (1883) placed Gymnosperms between Dicots and Monocots in their classification (General Plantarum). Van Tieghman (1898) gave the status of Major Division to the Gymnosperms. Tieghman also divided the whole Spermatophyta (seed plants) into two divisions namely Gymnosperms (Astigmatae) and Angiosperms (Stigmatae). Coulter and Chamberlain in 1912 divided the division Gymnosperms directly into seven orders namely (1) Cycadofilicales, (2) Bennettitales, (3) Cycadales, (4) Cordaitales, (5) Ginkoales, (6) Coniferales and (7) Gnetales.

Classification of Gymnosperms by Chamberlain (1934)

Ø  Chamberlain (1934) divided the Gymnosperms into TWO classes and each class into orders.

Ø  Gymnosperms were divided into TWO classes:

(1).      Cycadophyta

(2).      Coniferophyta

Chamberlain System of Classification

Class I : Cycadophyta

Ø  Class Cycadophyta includes both fossil and living forms.

Ø  The stem is unbranched and stumpy.

Ø  Leaves are large and pinnately compound.

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Botany lecture notes

Apical Meristem in Shoot: Structure and Organization


shoot-apical-meristem

Shoot Apical Meristem
Apical Organization of Shoot Meristem

Apical meristem

Ø  Apical meristem is a patch of meristematic tissue present in the apex (tips) of shoot and roots in plants.  

Shoot apex:

Ø  Shoot apex is the growing tip of the stem.

Ø  It is an undifferentiated region with meristematic cells.

Ø  From this region the plant growth proceeds.

Ø  The shoot apex also produces lateral organs such as leaves, branches and flowers.

Ø  Below the apical meristem, different tissue zones are progressively differentiated.

apical-meristem

Tissue zones in the shoot apex

Ø  Three main tissue zones are present on the shoot apex of plants, they are:

$.  Protoderm: Protoderm gives rise to the epidermis of the plant.

$.   Procambium: Procambium gives rise to primary vascular tissue (xylem & phloem).

$.   Ground meristem (fundamental meristem): The ground meristem gives rise endodermis, pericycle, cortex, medulla and pith.

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Secretory Tissue in Plants PPT (Structure, Classification and Examples)


Plant Science PPT

Secretory Tissue System in Plants PPT
(Structure, Classification, Functions and Examples of Secretory Tissues in Plants)

What is Plant Secretion? What are Secretory Tissues? How Plant Secretory System is Classified? Different Types of Secretory Systems in Plants, External vs Internal Secretory System in Plants, Glandular Trichomes, Nectaries and Hydathodes in Plants, Digestive Glands of Drosera, Salt Glands of Mangrove Plants, Colletors, Floral vs Extra-floral Nectaries, Water Stomata, Guttation, Internal Secretory Cells, Idioblasts, Cystoliths vs Raphides, Secretory Ducts and Cavities in Plants, Lysigenous vs Schizogenous Cavities in Plants, Laticifers in Plants, Articulate and Non-articulate Laticifers, Articulate Anastomosing and Articulate Non-anastomosing Laticifers, Chemical Composition of Latex and many more…

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Botany lecture notes

Secretory Tissue System in Plants (Structure, Classification and Functions + PPT)


secretory cells

Secretory Cells and Tissues in Plants
(Structure and Classification of Secretory Tissue System in Plants with Examples)

What are plant secretions?

Most of the plants release many substances from their cell cytoplasm to the exterior and they are called as Plant-secretions. Among these secretions, some are beneficial to the plant and some are not. The beneficial substances secreted from the plant parts are called as secretions. The chemical composition of plant secretions highly varies. The secretions may be water, nectar, salt, tannins, resins, latex, gums, digestive enzymes, hormones etc.

Secretory Cell/Tissue

Cells or tissue associated with or facilitate the secretion is termed as the secretory cell or secretory tissue. The structure, arrangement and the origin of secretory cells/tissues highly varies.

Classification of Secretory Tissues

Ø  The secretory tissue is broadly classified into two categories based on their position in the plant body. They are

(I). External secretory tissue

(II). Internal secretory tissue

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