"MONOCOT STEM FEATURES FOR CLASS XI (BIOLOGY) - EASY NCERT NOTES + LABELLED DIAGRAM"

 Important Notes on Monocot Stem

General Characteristics

• Belongs to monocotyledonous plants (e.g., maize, sugarcane, bamboo, grasses).

• No secondary growth due to the absence of a vascular cambium.

• Vascular bundles are scattered throughout the ground tissue.

• The stem is usually herbaceous, but some may become woody (e.g., palms).

Anatomical Features (TS - Transverse Section)

1. Epidermis

   • Outermost layer; single-layered, made of compactly arranged cells.

   • Covered with a cuticle to prevent water loss.

   • May contain stomata and trichomes (in some species).

2. Hypodermis

   • Usually consists of sclerenchyma cells (mechanical support).

   • Lies just beneath the epidermis.

3. Ground Tissue

   • No clear differentiation into cortex, endodermis, pericycle, etc.

   • Entire area between hypodermis and vascular bundles is parenchymatous.

   • Stores food and may help in photosynthesis.

4. Vascular Bundles

   • Scattered in the ground tissue (atactostele).

   • Each bundle is conjoint, collateral, and closed (no cambium).

   • Surrounded by a sclerenchymatous bundle sheath for strength.

   • Xylem is oriented towards the center (endarch), phloem towards the outside.

5. Pith

   • Not distinct as in dicots; ground tissue is uniform.

Examples of Monocot Stems: Maize, Wheat, Sugarcane, Banana, Bamboo

                       

Key Differences from Dicot Stem

Feature	Monocot Stem	Dicot Stem
Vascular bundles	Scattered	Arranged in a ring
Cambium	Absent	Present
Secondary growth	Absent	Present
Ground tissue	Undifferentiated	Differentiated (cortex, pith)
Bundle type	Closed	Open