Question

Describe the different types of vascular bundles.

Answer 1

Types of vascular bundles :

1) Radial: In this type, xylem and phloem form separate bundles alternating with each other i.e. they lie on different radii. The bundles are separated by conjunctive tissue.

2) Conjoint: When xylem and phloem combine into one bundle, it is known as a conjoint bundle. These are of following types

• Collateral - When xylem and phloem combine together and life on the same radius, it is called collateral. Xylem occupies the internal position and phloem occupies the external position. If cambium is present, it is said to be open type as in dicot stems and when cambium is absent, it is said to be closed type
• Bicollateral - Phloem and cambium lie on both sides of the xylem.
• Concentric - Xylem and phloem are concentric i.e., one surrounds the other. When xylem lies in the centre completely surround by the phloem, it is known as amphicribal and when phloem lies in the centre and xylem surrounds it completely, it is known as amphivasal.