Difference Between Amphicribral and Amphivasal

The key difference between amphicribral and amphivasal is that in an amphicribral arrangement, phloem encircles the xylem while in an amphivasal arrangement, xylem encircles the phloem.

Vascular tissues are the conducting elements of vascular plants. There are two main types of conducting elements as xylem and phloem. Xylem is responsible for the conduction of water and minerals while phloem is responsible for the transport of foods/carbohydrates throughout the plant. Generally, in stems and roots, xylem and phloem are found together in vascular bundles. Based on the arrangement of xylem and phloem in vascular bundles, there are four types of vascular bundles: bicollateral, amphicribral and amphivasal. In amphicribral arrangement, xylem is surrounded by a ring of phloem while in amphivasal arrangement, phloem is surrounded by a ring of xylem.

CONTENTS

1. Overview and Key Difference
2. What is Amphicribral 
3. What is Amphivasal
4. Similarities Between Amphicribral and Amphivasal
5. Side by Side Comparison – Amphicribral vs Amphivasal in Tabular Form
6. Summary

What is Amphicribral (Hadrocentric Bundle)?

Amphicribral arrangement is one of the four types of xylem and phloem arrangement in vascular bundles. In amphicribral arrangement, xylem is surrounded by a ring of phloem. In other words, phloem encircles the strand of xylem. This type of vascular bundle is also known as a hadrocentric bundle. In fact, it is a type of concentric vascular bundles.

Moreover, amphicribral arrangement is a closed vascular system because there is no cambium in between the xylem and phloem. Selaginella is a plant that has amphicribral vascular bundle arrangement.

What is Amphivasal (Leptocentric Bundle)?

Amphivasal arrangement is a vascular bundle arrangement in which the phloem is surrounded by a ring of xylem. In other words, xylem encircles the central strand of phloem in amphivasal arrangement. This arrangement is also known as the leptocentric bundle.

Similar to amphicribral arrangement, amphivasal arrangement is also a closed system without a cambium. Dracaena and Yucca, Begonia and Rumex are plants that have amphivasal arrangement.

What are the Similarities Between Amphicribral and Amphivasal?

• Amphicribral and amphivasal arrangements are two types of concentric vascular bundles.
• In these two types, one type of vascular tissue surrounds the other type of vascular tissue.
• Both types are closed vascular bundles.
• There is no cambium between xylem and phloem in both types.
• Moreover, they are conjoint type vascular bundles.

What is the Difference Between Amphicribral and Amphivasal?

Amphicribral vascular system has a central strand of xylem that is surrounded by a ring of phloem. In contrast, amphivasal vascular system has a central strand of phloem that is surrounded by a ring of xylem. Therefore, phloem surrounds xylem in amphicribral arrangement while xylem surrounds phloem in amphivasal bundle. So, this is the key difference between amphicribral and amphivasal. Hadrocentric bundle is a synonym of amphicribral while leptocentric bundle is a synonym of amphivasal.

The following infographic presents more comparisons related to the difference between amphicribral and amphivasal.

Summary – Amphicribral vs Amphivasal

Amphicribral and amphivasal are two types of concentric vascular bundles. In both types, one type of vascular tissue encircles the other type of vascular tissue. Moreover, they are closed vascular bundles that lack a cambium. Amphicribral vascular bundle is a vascular bundle in which phloem encircles the central strand of xylem. In contrast, amphivasal vascular bundle is a vascular bundle in which xylem encircles the central strand of phloem. Thus, this is the key difference between amphicribral and amphivasal.

Reference:

1. “4 Main Types Of Vascular Bundle | Plants”. Biology Discussion, 2020, Available here.
2. “Plant Vascular System Development”. Msu.Edu, 2020, Available here.

Image Courtesy:

1. “Perennial Monocot Stem: Amphivasal Vascular Bundle in Acorus Rhizome” By Berkshire Community College Bioscience Image Library (Public Domain) via Flickr