Monocots vs Dicots

The Tissue Type Systems

• Discusses tissues based on the types of cells present in them
• Tissue types vary depending on their location on the plant and their structures and functions
• On the basis of their structure and location, there are 3 types of tissue systems; epidermal, ground/fundamental, and vascular/conducting tissue systems.

Epidermal Tissue System

• Forms the outermost covering for the whole plant body and is mostly comprised of epidermal cells, stomata, and trichomes (hairs)
• The epidermis is the outermost layer of the primary plant body, made up of closely arranged cells forming a continuous layer
• Epidermal cells are usually a single layer of parenchymatous cells with a small amount of cytoplasm
• The cell wall on the outside of the epidermis is often covered with a waxy layer called the cuticle, preventing water loss
• The cuticle is absent in roots

Stomata

• Stomata in the epidermis regulate the process of transpiration and gaseous exchange
• Guard cells enclose each stomata pore, and are dumbbell-shaped in grasses
• Outer walls of guard cells are thin, while inner walls (towards the stomata pore) are thicker
• Guard cells possess chloroplasts and regulate the opening and closing of stomata
• Subsidiary cells are specialized epidermal cells in their shape and size that surround guard cells
• Guard cells and surrounding subsidiary cells together are called the stomatal apparatus

Further Notes on Plant Tissues

• The outermost layer of the dicotyledonous root is the epiblema, which has some unicellular root hairs
• The cortex consists of thin-walled parenchyma cells with intercellular spaces
• The innermost layer of the cortex, the endodermis, comprises barrel-shaped cells without any intercellular spaces
• Tangential and radial walls of endodermal cells possess depositions of water-impermeable, waxy material suberin, in the form of Casparian strips
• Next to the endodermis lies a few layers of thick walled parenchymatous cells referred to as the pericycle, which aids in the initiation of lateral roots and vascular cambium during secondary growth
• The pith is small or inconspicuous
• Conjunctive tissue refers to the parenchymatous cells located between the xylem and phloem

Strichomes

• Epidermal cell elongations in roots are root hairs, which aid in absorbing water and minerals from the soil.
• Epidermal cells on the stem form trichomes, which are usually multicellular and may be branched, soft, or stiff.
• Trichomes help prevent water loss due to transpiration and can be secretory

Ground Tissue System

• Consists of tissues like parenchyma, collenchyma, and sclerenchyma.
• Parenchymatous cells are usually present in the cortex, pericycle, pith, and medullary rays in the primary stem and roots.
• In leaves, the ground tissue consists of thin-walled, chloroplast-containing cells called mesophyll.

Vascular Tissue System

• Consists of complex tissues, phloem and xylem.
• The xylem and phloem together constitute a vascular bundle
• Vascular bundles in dicotyledons have cambium present between xylem annd pholem
• Because of the presence of cambium they possess the potential to form secondary xylem and tissues, and are called open vascular bundles.
• Monocotyledons do not have cambium present

The arrangement of xylem and pholem

• Xylem and pholem arrange in an alternate manner along different radii, the arrangement is called "exarch", as in roots.
• If xylem and pholem are jointly situated along the same radii of a vascular bundle, it is called "conjoint".
• Conjoint vascular bundles usually have pholem located only on the outer side of xylem.

Anatomy of Dicotyledonous and Monocotyledonous Plants

• The transverse section of a typical young dicot stem shows that the epidermis is the outermost protective layer of the stem
• A thin layer of cuticle covers the epidermis
• The epidermis may bear trichomes and a few stomata.
• Cells between the epidermis and pericycle constitute the cortex, and consist of three sub-zones.

Monocot vs. Dicot: Plant Anatomy

Other details on Roots and leafs

• Monocot fruit and dicot root have limited growth
• Monocot roots have numerous roots springing from the base
• Dicot roots have prominent main roots (tap root) which bears lateral roots in a basipetal order.
• Internal ground tissues are present
• Vascular bundles are scattered throughout the cortex
• Dicot roots have comparatively fewer xylem bundles, with a prominent main root.
• Monocot embryo consists of a single cotyledon