Q.Girth of a Maize plant does not increase over a period of time. Justify.

Stem girth increases over time only when a plant has active secondary growth, and secondary growth depends on the presence of cambium.

Step 1. Maize's classification. The chapter lists Zea mays (maize) as an example of Monocotyledonae.

Step 2. Vascular bundle type in Monocots. In Monocotyledonae, the vascular bundles are conjoint, collateral and of the closed type — meaning there is no cambium between the xylem and phloem.

Step 3. Consequence for secondary growth. Because cambium is the tissue responsible for producing new xylem and phloem (and hence increasing girth), its absence means that — except in a few unusual Monocots — secondary growth simply does not occur. …

Trace girth increase back to secondary growth, secondary growth back to cambium, and note that Mono …

• Confusing 'closed' vascular bundles (no cambium, Monocots) with 'open' vascular bundles (cambium present, Dicots). …