T.S. Dicot Stem

Key Anatomical Features

Epidermis: The outermost single layer of parenchymatous cells, covered by cuticle for protection and water loss prevention. Trichomes (multicellular hairs) and some stomata are commonly present.​

Hypodermis: Lies beneath the epidermis, consists of several layers of collenchymatous cells, which are thickened at the corners, providing mechanical strength and elasticity to the stem.​

Cortex: Composed of three zones:

Outer hypodermis (collenchyma).

General cortex (parenchymatous cells with intercellular spaces).

Endodermis (barrel-shaped cells, starch sheath with abundant starch grains).​

Pericycle: Found just inside the endodermis, often as patches of sclerenchymatous tissue above the phloem.​

Vascular Bundles: Arranged in a ring (ring formation is a hallmark of dicot stems), each is conjoint, collateral, open (has a cambium), and endarch (protoxylem towards the center). Cambium enables secondary (thickness) growth.​

Phloem: Outside.

Cambium: Central strip allowing secondary growth.

Xylem: Arranged towards the inside.

Medullary Rays (Pith Rays): Parenchymatous tissues radiating between vascular bundles, facilitating lateral transport of substances.​

Pith: Central region, made up of large, round parenchymatous cells (food storage), often well-developed in dicot stems.