Describe the T.S of a dicot stem.

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The T.S. of a typical young dicotyledonous stem shows
Epidermis
Cortex
Stele
I) Epidermis : It is the outermost protective layer.
- It is covered with a thin layer of cuticle.
- It may bear trichomes and a few stomata.
II) Cortex : The cells arranged in multiple layers between epidermis and pericycle constitute the cortex. It consists of three sub zones
Hypodermis,
General cortex
Endodermis
- a. Hypodermis : It consists of a few layers of collenchymatous cells. It present just below the epidermis. It provides mechanical strength to the young stem.
- b. General cortex : It is present below the hypodermis. It consist of rounded thin walled parenchyma cells with conspicuous intercellular spaces.
- c. Endodermis : It is the innermost layer of the cortex. The cells are rich in starch grains. This layer is also referred to as the starch sheath.
III) Stele : It is the central part of stem. It consists of
a) Pericycle b) Vascular bundles c) Medulla d) Medullary rays
- Pericycle : It is present on the inner side of the endodermis. It is present above the phloem in the form of semilunar patches of sclerenchyma.
- Vascular bundles : A large number of vascular bundles are arranged in a ring. The ring arrangement of vascular bundles is a characteristic of dicot stem. Each vascular bundle is conjoint, open, and with endarch protoxylem.
- Medulla/pith : It is large number of rounded, parenchymatous cells with large intercellular
  spaces. It occupy the central portion of the stem.
- Medullary rays : In between the vascular bundles there are a few layers of radially placed parenchymatous cells, which constitute medullary rays.

Describe the T.S of a dicot stem.

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