Introduction to Plant Anatomy

Introduction to Plant Anatomy

• Plants are composed of various tissues organized into organs.
• Study of internal structure is known as anatomy.
• Monocots and dicots differ in terms of seed structure, vascular bundle arrangement, and leaf venation.

The Tissues

• Tissues are groups of cells with a common origin and function.
• Tissues are classified into meristematic and permanent tissues based on cell division capability.

Meristematic Tissues

• Meristematic tissues are responsible for plant growth.
• Located at root and shoot tips, responsible for primary growth.
• Apical meristems contribute to elongation and formation of new organs.
• Intercalary meristems are found between mature tissues, particularly in grasses, and aid in regeneration after grazing.
• Lateral meristems are responsible for secondary growth, producing secondary tissues like wood and bark.
• Examples of lateral meristems include vascular cambium and cork cambium.

Permanent Tissues

• Composed of mature cells that no longer divide.
• Divided into simple and complex tissues.

Simple Tissues

• Made of one cell type; includes parenchyma, collenchyma, and sclerenchyma.
• Parenchyma functions in storage, photosynthesis, secretion, and cell division.
• Parenchyma cells are thin-walled and can be isodiametric.
• Collenchyma provides support to growing parts; cells have thickened corners.
• Sclerenchyma provides mechanical support; consists of thick-walled, dead cells.
• Sclerenchyma includes fibers and sclereids, found in various plant parts.

Complex Tissues

• Composed of multiple cell types working together.
• Includes xylem and phloem, essential for transporting substances throughout the plant.
• Xylem conducts water and minerals; provides mechanical strength.
• Xylem is composed of tracheids, vessels, fibers, and parenchyma.
• Phloem transports food from leaves to other parts.
• Phloem is composed of sieve tube elements, companion cells, fibers, and parenchyma.

The Tissue System

• Three main systems: epidermal, ground, and vascular.

Types of Tissue Systems

• Epidermal Tissue System forms the outer covering of the plant; includes epidermal cells and stomata.
• Stomata regulate gas exchange and transpiration.
• Ground Tissue System comprises all tissues except epidermis and vascular bundles.
• Ground Tissue System includes parenchyma, collenchyma, and sclerenchyma.
• Vascular Tissue System is composed of xylem and phloem; forms vascular bundles.
• Vascular bundles can be open or closed, depending on the presence of cambium.

Anatomy of Dicotyledonous and Monocotyledonous Plants

Dicotyledonous Root Anatomy

• Features include epiblema, cortex, endodermis, pericycle, and vascular bundles.
• Vascular bundles consist of xylem and phloem arranged in a specific pattern.

Monocotyledonous Root Anatomy

• Similar to dicot roots but typically has more xylem bundles.
• Pith is larger and more developed; lacks secondary growth.

Dicotyledonous Stem Anatomy

• Epidermis covered with cuticle; cortex has three regions: hypodermis, general parenchyma, and endodermis.
• Vascular bundles arranged in a ring; includes cambium for secondary growth.

Monocotyledonous Stem Anatomy

• Scattered vascular bundles surrounded by a bundle sheath.
• Lacks phloem parenchyma; features large parenchymatous ground tissue.

Leaf Anatomy

• Composed of epidermis, mesophyll, and vascular system.
• Dorsiventral Leaf Structure has mesophyll including palisade and spongy parenchyma for photosynthesis, and stomata present on both surfaces.
• Isobilateral Leaf Structure has mesophyll that is not differentiated and stomata present on both surfaces.
• Bulliform cells help in water regulation in isobilateral leaves.

Secondary Growth

• Involves increase in girth due to lateral meristems.
• Primarily occurs in dicotyledons and gymnosperms.
• Vascular cambium is responsible for producing secondary xylem and phloem, which contribute to the thickening of the stem.
• Vascular cambium forms a cambial ring through intrafascicular and interfascicular cambium.
• Cork cambium develops to replace outer layers as the plant grows.

Explore the fascinating world of plant anatomy, focusing on the structure and function of various tissues. This quiz covers key concepts such as meristematic and permanent tissues and the differences between monocots and dicots. Test your knowledge on plant growth and the organization of tissues within plants.