Question

Differentiate amphivasal and amphicribal

Answer 1

Concentric Bundle:

A vascular bundle in which one type of vascular tissue surrounds the other is known as concentric bundle.

In this bundle xylem either encircles or is encircled by phloem and accordingly the following two types are recognized:

(a) Amphivasal bundle:

A vascular bundle in which xylem encircles the central strand of phloem is known as amphivasal bundle, also called leptocentric bundle. Ex. Dracaena, Yucca.

(b) Amphicribral bundle:

A vascular bundle in which phloem encircles the central strand of xylem is called as amphicribral bundle, also known as hadrocentric bundle. Ex. Selaginella.

The concentric bundles, either amphivasal or amphicribral, are closed as there is no cambium in between xylem and phloem.