Chapter 20, Problem 39A

Summary Introduction

To describe:

Importance of mycorrhizae for the colonization of lands by plants,

Introduction:

Mycorrhiza: It is a symbiotic association between a root of some plants and fungi. It helps the plant to uptake phosphorus and nitrogen.

Explanation of Solution

The autotrophs like plants depend on various raw materials such as carbon-nitrogen, minerals, etc. These nutrients plants take up from the soil. In the early plants, fungus provided raw material such as nitrogen and phosphorus from the soil and in return takes up carbohydrates as the source of food.

These are proved by the fossils of the Aglaophyton major, which shows the presence of mycorrhiza.