ANATOMY OF DICOTYLEDONOUS AND MONOCOTYLEDONOUS PLANTS

ANATOMY OF DICOTYLEDONOUS AND MONOCOTYLEDONOUS PLANTS

·         For batter understanding, we study a transverse section of roots, stems and leaves at mature stage of plants.

For Roots:-

Dicotyledons

·         Epidermis- The outermost protective layer with root hairs.

·         Then Cortex- It consist of parenchymatous cells having thin wall. It is many layered with intracellular spaces.

·         Then Endoderm- It consists of barrel shaped endodermal cells of impermeable cell wall having waxy material called suberin. It is inner most layer of cortex which is single layered.

·         Then Pericycle- It consists of parenchymatous cells of thick cell wall. These cells are responsible for secondary growth.

·         Then Xylem and Phloem- It is present as 2-4 patches. In between xylem and phloem a parenchymatous cells are present called conjuctive tissue.

Monocotyledons

·         Its tissue arrangement is almost same as Epidermis, Cortex and pericycle except following as

·         Endodermis is thicker than dicot

·         Xylem and Phloem- It is more than 6 bundled.

·         Pith is large and well developed

·         It doesn’t take part in secondary growth.

For stem:-

Dicotyledons

·         Epidermis- It is outermost protective layer. It externally covered with cuticle having stomata.

·         Then Cortex- It divisible into three layers as-

1.       Hypodermis- It consists of collenchyma cells and provide mechanical strength to stem.

2.       Cortical layer- It consists of rounded parenchymatous cells having thin cell wall.

·         Then  Endodermis- It consists of endodermal cells having a lot of starch

·         Then Pericycle- It consist of sclerenchymatous cells as a semi-lunar patches.

·         Then Vascular Bundle- It consists of xylem and phloem. It is arranged in a ring which is characteristic feature of dicot stem.

·         Then Pith- It consist of parenchymatous cells with large intracellular spaces. It is the central position of the dicot stem.

Monocotyledons

·         It is different from dicot stem only its Epidermis is same as dicot.

·         Then Cortex only hypodermis- It is consists of sclerenchymatous cells

·         Then Ground Tissue- It consists of parenchymatous tissue and present in large quantity in circular area.

·         Then Vascular Bundles- It is present in the ground tissues and consists of xylem and phloem. It is rounded and larger at central portion than peripheral region.

For Leaf:-

Dicotyledons (Dorsiventral Leaf)

·         Lamina consists of three parts – Epidermis, Mesophyll, Vascular system.

·         Epidermis- It is outermost protective layer. It present at upper surface called adaxial epidermis and at lower surface called abaxial epidermis. Abaxial epidermis bears more stomata than adaxial epidermis.

·         Mesophyll- It is present between adaxial and abaxial epidermis. It consists of parenchymatous cells having chloroplast so take part in photosynthesis. There are many large spaces or air cavities are present between cells. Its cell is divisible into two types-

1.       Palisade Parenchyma- It is elongated cells, which arrange ventrally and parallel to each other.

2.       Spongy Parenchyma- It is oval or rounded cells, arranged loosely and below palisade parenchyma cell.

·         Vascular System- Is consists of vascular bundles seen in the veins and midrib. The vascular bundle surrounded by a layer of thick walled called Bundle Sheath cells and its size is depend on size of veins.

Monocotyledons (Isobilateral Leaf)

·         It is almost similar to dicot leaf, only a little differences is occurred as

·         In gases, some adaxial epidermis along with veins modified into large, empty, colourless cells called bulliform cell.

·         Mesophyll doesn’t differentiated.

About AMS Official