Question
With suitable diagram explain the structure of dicot stem. Write main differences between dicot and monocot stems.
✓
Answer
Dicotyledonous Stem:
- Epidermis: The transverse section of a typical young dicotyledonous stem shows that the epidermis is the outermost protective layer of the stem. Covered with a thin layer of cuticle, it may bear trichomes and a few stomata.
- Cortex: The cells arranged in multiple layers between epidermis and pericycle constitute the cortex. It consists of three sub-zones. The outer hypodermis, consists of a few layers of collenchymatous cells just below the epidermis, which provide mechanical strength to the young stem. Cortical layers below hypodermis consist of rounded thin walled parenchymatous cells with conspicuous intercellular spaces. The innermost layer of the cortex is called the endodermis. The cells of the endodermis are rich in starch grains and the layer is also referred to as the starch sheath. Pericycle is present on the inner side of the endodermis and above the phloem in the form of semi-lunar patches of sclerenchyma. In between the vascular bundles there are a few layers of radially placed parenchymatous cells, which constitute medullary rays.
- 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. A large number of rounded, parenchymatous cells with large intercellular spaces which occupy the central portion of the stem constitute the pith.
|
S.No.
|
Dicot Stem
|
Monocot Stem
|
|
i.
|
Vascular bundles are arranged in a ring.
|
Vascular bundles are scattered.
|
|
ii.
|
Secondary growth takes place.
|
Secondary growth does not happen.
|
|
iii.
|
Wood is formed.
|
Wood is not formed.
|
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
Distinguish between the following: Glycolysis and Citric acid cycle
Draw a labelled diagram of the reproductive organs of an earthworm.
What is aestivation? Describe the various types of aestivation with diagram.
What is stomatal apparatus? Explain the structure of stomata with a labelled diagram.
Name the product formed by esterification of glycerol with a fatty acid. Also draw its structure.
By describing the characteristics found in Bryophytes plants describe liverworts and mosses.
Explain how minerals are transported to various parts of plants?
Explain Rh-incompatibility in humans.
How many types of plastids are there on the basis of colour? Draw a diagram of chlorophyll and describe it.
The stomatal pore is guarded by two kidney shaped guard cells. Name the epidermal cells surrounding the guard cells. How does a guard cell differ from an epidermal cell? Use a diagram to illustrate your answer.