Chapter 21.3, Problem 4MI

Summary Introduction

To compare:

The present-day club mosses with their ancestors and describe the structures found in present-day plants.

Introduction:

Club mosses are one of the most primitive vascular plants. They first appearing in the fossil record around 400 million years ago. They may be tiny today, but during the Carboniferous period club mosses were height of 100 feet.  

Answer to Problem 4MI

Comparison of club moss with fossil evidence and present day-plants

	Club moss
1 Fossil Evidence	Ancestors were once tree-sized plants. Formed a large part of Paleozoic forests.
2 Present day plants	Usually less than 30 cm tall plants. Dominant phase is sporophyte generation.<
3 Structures	Roots grow from the base of stem. Stems may be branched or unbranched Small, scaly leaf-like structures with vascular tissue

Explanation of Solution

Fossil evidence:

As per the fossil record club mosses were appeared around 400 million years ago during the Carboniferous period about 350 million years ago. They like large trees and could attain a height of 100 feet.

Present day-plants:

Present day plants are small, non-woody plants without true leaves. They grow in shady areas with moist soil, but can survive dry conditions. Plant produce spores and plant body is the sporophyte.

Structures:

Small evergreen herbs with needlelike or scale-like leaves. Many species have cone-like strobili. Each strobilus is with a kidney-shaped spore capsule at its base. The sporophyte produces one kind of spores.