Question

Identify the incorrect order of components with reference to their arrangement from outside to inside in a woody dicot stem.

• A. Epiblema, cortex, pericycle, endodermis
• B. Epidermis, hypodermis, phellogen, phelloderm
• C. Epidermis, phellem, phellogen, endodermis
• D. Epidermis, phellem, phellogen, phelloderm

Answer 1

The correct option is A Epiblema, cortex, pericycle, endodermis

A woody dicot stem has an outer epidermis. This layer is covered by cuticle.

Epidermis is followed by the hypodermis. Below hypodermis, lies the cortex. The cortex is divided into the outer cortex and inner cortex.

Innermost layer of cortex is called endodermis. Innerside of the endodermis has pericycle.

During secondary growth, the stems increases in girth. This breaks down the outer cortical and epidermal layers. A new layer of cork cambium or phellogen develops in its place.

Phellogen cuts off both the cortical and epidermal layers. The outer cells differentiate into cork or phellem. The inner cells differentiate into secondary cortex or phelloderm.
Phellogen, phellem and phelloderm is together called periderm.

The epiblema is the outermost layer found in the anatomy of roots.