Tag: venation

Questions Related to venation

Parallel venation is observed mostly in

botany leaf - external morphology venation arrangement of leaves morphology of leaf

  1. Monocot plants

  2. Dicot plants

  3. Thallophytes

  4. Bryophytes

Show answer
Correct Option: A
Explanation:
Venation is the arrangement of veins in a leaf. Parallel venation is where the secondary veins run parallel to each other and are connected laterally by minute and straight veinlets. This type of venation is mostly seen in monocots, for example, grass. 
So, the correct answer is 'Monocot plants'

In a leaf with reticulate venation

botany leaf - external morphology venation arrangement of leaves morphology of leaf

  1. Veins forms a network on the leaf

  2. Veins run parallel to the midrib

  3. Veins run horizontal to the midrib

  4. Veins criss-cross each other in an irregular pattern

Show answer
Correct Option: A
Explanation:

Venation is the arrangement of veins in a leaf. In reticulated venation, veins are interconnected and form a web-like network. There is a prominent vein called the midrib from which many small veins arise which finally form a net like structure in the lamina. This kind of venation is seen in dicots.

In a leaf with parallel venation

botany leaf - external morphology venation arrangement of leaves morphology of leaf

  1. Veins form a network on the leaf

  2. Veins run parallel to the midrib

  3. Veins run horizontal to the midrib

  4. Veins crisscross each other to from an irregular pattern

Show answer
Correct Option: B
Explanation:

Venation is the arrangement of veins in a leaf. Parallel venation is where the secondary veins run parallel to each other and are connected laterally by minute and straight veinlets. This type of venation is mostly seen in monocots.

Parallel venation is a characteristic of moncots. which of the following is an exception to this generalization?

botany leaf - external morphology venation arrangement of leaves morphology of leaf

  1. Smilax

  2. Colocasia

  3. Alocasia

  4. All of these

Show answer
Correct Option: D
Explanation:

In case of parallel venation, the veins run parallel to each other and network is not formed. This type of venation is the characteristic feature of monocots. There are few exceptions, e.g., Smilax, Colocasia, Alocasia, Dioscorea, etc.
Correct option is D.

Venation is a term used to describe the pattern of arrangement of

botany leaf - external morphology venation arrangement of leaves morphology of leaf

  1. Floral organs

  2. Flower in inflorescence

  3. Veins and veinlets in a lamina

  4. All of the above

Show answer
Correct Option: C
Explanation:

The arrangement of veins and veinlets on the lamina of the leaf is called as venation.
Correct option C.

Which one of the following is correct?

botany leaf - external morphology venation arrangement of leaves morphology of leaf

  1. In dorsiventral leaf, stomata are on lower (abaxial) surface.

  2. Protoxylem disintegrates to produce lacuna (lysigenous) in monocot stem.

  3. Reticulate venation in dicot leaf, parallel venation in monocot leaf.

  4. All of the above

Show answer
Correct Option: D
Explanation:
a) Dorsiventral leaf has stomata only on the lower surface because it is more often in the shade and so it is cooler, which means evaporation won't take place as much. 
b) Protoxylem lacuna is a space surrounded by parenchyma cells in the protoxylem of a vascular bundle. Appears in some plants after the protoxylem has ceased to function, after these elements have been stretched and torn, thus forming the cavity (lacuna) in monocot stem. 
c) Leaf veins are arranged either in parallel through the length of the leaf or in a reticulate arrangement throughout the leaf. In most species, monocot leaves have parallel arrangement while dicots have reticulate venation of leaves.
So, the correct answer is 'All the above'.