Rapid development in complexity, variety and numbers through the Palaeozoic caused a green revolution over the surface of the globe. Early plants lacked leaves, flowers and roots. The first land plants, such as Cooksonia , were simply stems with spore capsules at their tips. There were uncomplicated and fragile, but they transformed the surface of the world. Early land plants reproduced by means of spores .
Spores are tiny, light and have a durable protective wall.
They are easily dispersed by wind and water. The first know spores are 430 million years old. Most early plants are preserved as a thin carbon film in the rocks. These specimens, however, have retained their three dimensional structure. Vascular cells are clearly visible when the stems are examined under a microscope.