Evolution of Land Plant Diversity Major Innovations and Lineages through Time

Plant diversity has evolved and is evolving on the earth today according to the processes of natural selection. All basic "body plans" of vascular plants were in existence by the Early Carboniferous, approximately 340 million years ago, and each major radiation occupied a particular habitat type, for example, wetland versus terra firma, pristine versus disturbed environments. Today the great species diversity we see on theplanetis dominated by just a few of these hasicplant types. This chapter sets the stage to understanding the origin and radiation of plant diversity on the earth before the significant influence of humans. The implication is that plants may become more diverse in the number of species level over time, but less diverse in overall form. The history of life tells us that plants that are dominant and diverse today will certainly be inconspicuous or even -' tinct in the distant future.