Yale University
Yale New Haven Teachers Institute: Evolution of Plants
An extensive coverage of the evolutionary history of plants. Click on a topic in the outline and you'll go to a good discussion on this material.
Estrella Mountain Community College
Maricopa Community College: Nonvascular Plants and Nonseed Vascular Plants
Very detailed outline describing several aspects of plant diversity, including vascular vs. nonvascular, evolutionary adaptations, homosporous and heterosporous life cycles, and specific information on some ancient species (Lycophytes,...
Other
Coastal Zone: Plant Evolution
A good slide show which covers the basics of plant evolution. Includes discussion of the major portions of what plants have done to adapt over the eons.
CK-12 Foundation
Ck 12: Biology: Early Evolution of Plants
[Free Registration/Login may be required to access all resource tools.] Describes how plants evolved from living in the oceans to living on land.
Other
Natural Science: Early Branch of Green Plant Evolution
Recent discovery and theroy that changes the conventional explanation for the evolution of plants.