Botany lecture notes

Root Stem Transitions in Plants with PPT


Root Stem Transitions in Plants

Root Stem Transition in Plants (with PPT)
(Theories of Anatomical Transition from Root to Stem In Angiosperms)

Root and stem form a continuous structure in plants called the axis. The vascular tissue in root is radial (xylem and phloem arranged separately in different radii) whereas in the stem is conjoint (xylem and phloem are arranged together in same radii as vascular bundles). Thus, there should be a region in the axis where the vascular structures of the root and the stem meet and merge together. This peculiar region is called the Root-Stem Transition Zone. The current post describes the various types of root-stem transitions found in Angiosperms.

Ø  The epidermis, cortex, endodermis, pericycle and the secondary vascular tissue are continuous from root to stem.

Ø  Only the primary vascular tissue in the axis undergoes a change in their position and orientation.

Ø  The exarch arrangement of xylem in root changes to endarch position in the stem.

Ø  In the transition zone, the vascular tissue undergoes many changes such as Forking, Multiplication, Rotation and Fusion.

Ø  The vascular tissue also increases their diameter.

Ø  The exact position of the transition zone is different in different plants.

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Botany lecture notes

Dicot Leaf (Dorsiventral Leaf) Structure with PPT


Anatomy of Dicot Leaf PPT

Dicot Leaf Cross Section (Dorsiventral Leaf)
(Anatomical Structure of a Dicot Leaf- Ixora, Mangifera, Hibiscus)

Ø  Leaves are structurally well adapted to perform the photosynthesis, transpiration and gaseous exchange.

Ø  A leaf composed of:

(1). Leaf blade: also called leaf lamina is the flattened expanded part of the leaf chiefly composed of mesophyll tissue and vascular bundles.

(2). Petiole: the stack of leaf

Ø  Based on the differentiation of mesophyll, two categories of leaves are present among Angiosperms

(1). Dorsiventral Leaf

(2). Isobilateral Leaf

(1). Dorsiventral Leaf:

Ø  Also called bifacial leaf.

Ø  They have anatomically different dorsal and ventral sides.

Ø  The mesophyll tissue is differentiated into upper palisade and lower spongy tissues.

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Botany lecture notes

Anatomy of Dicot Root Primary Structure with PPT


Dicot root under microscope

Anatomy of Dicot Root (Primary Structure)
(Primary Anatomical Structure of a Dicot Root- Tinospora / Ficus Cross Section under Microscope)

Ø  Anatomy of a dicot root primary structure can be studied through a Cross Section (CS).

Ø  Anatomically, the primary structure in a dicot root is differentiated into the following tissue zones:

(1).   Root cap

(2).   Epidermis

(3).   Cortex

(4).   Endodermis

(5).   Pericycle

(6).  Vascular Tissue

(7).   Conjunctive Tissue

(8).   Pith

Record Diagram for Dicot Root

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Botany lecture notes

Anatomy of Monocot Root Cross Section Key Points with PPT


Monocot Root Cross Section

Anatomy of Monocot Root
(Monocot Root Cross Section Under Microscope with Diagram)

Ø  The anatomical features of a monocot root can be studied through a cross section (CS) through the root.

Ø  Anatomically, the monocot root has been differentiated into the following parts:

(1).    Epidermis

(2).    Cortex

(3).    Endodermis

(4).    Pericycle

(5).    Vascular Tissue

(6).    Conjunctive Tissue

(7).     Pith

(1). Epidermis

Ø  Epidermis in the root is also known as epiblema, piliferous layer and rhizodermis.

Ø  It is the outermost layer in the root, composed of closely packed parenchymatous cells.

Ø  Usually, the epidermis is single layered with thin walled cells.

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Botany lecture notes

Difference between Sieve Tubes and Sieve Cells- A Comparison Table


sieve cells and sieve tubes differences

Sieve Tubes vs Sieve Cells
(Similarities and Differences between Sieve Tubes and Sieve Cells)

Phloem is a permanent vascular tissue system associated with the conduction of food materials in plants. It is a complex tissue composed of more than one type of cells namely sieve elements, companion cells, phloem fibres and phloem parenchyma. Among these cells, the sieve elements are the most specialized cells in the phloem performing the conduction of food materials. There are two types of sieve elements are described among vascular plants based on structural complexity and evolutionary significance. They are (1) Sieve Cells and (2) Sieve Tubes. The present post describes the similarities and differences between sieve cells and sieve tubes as a comparison table.

Similarities between Sieve Cells and Sieve Tubes

Ø  Both sieve cells and sieve tubes components of phloem.

Ø  Both are the sieve elements (a category of phloem cells).

Ø  Both sieve cells and sieve tubes transport food materials.

Ø  Both are living cells.

Ø  Both cells have thin primary cell wall (secondary thickening absent).

Ø  Both contain dense granular protoplasm.

Ø  Nucleus is absent in both sieve cells and sieve tubes.

Ø  Both present in primary and secondary phloem.

Difference between Sieve Cells and Sieve Tubes

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