Q.State three anatomical differences between the stems of a dicotyledonous and a monocotyledonous plant.

Comparing a dicot and a monocot plant's anatomy across the root, stem and leaf shows that their many structural differences are not a random list of unrelated facts, but trace back to just two underlying causes.

The first is how many vascular bundles are formed and how they are arranged: a dicot root forms a compact, limited number of xylem patches around a small or absent pith, while a monocot root forms many more (polyarch) around a large, persistent pith; a dicot stem arranges a limited number of bundles in a single ring around a large pith with a differentiated cortex, while a monocot stem scatters numerous bundles through an undifferentiated ground tissue with no true cortex-pith distinction.

The second is the presence or absence of a vascular cambium: a dicot's bundles are open (cambium present), letting them join into a continuous ring and drive secondary growth over years; a monocot's bundles are closed (no cambium), so the plant generally cannot thicken beyond its primary structure. This same distinction indirectly decides even the hypodermis type -- collenchymatous (flexible, since the dicot stem will thicken later) in a dicot stem, sclerenchymatous (rigid from the start) in a monocot stem. …