Why It Matters: Plant Diversity

Why differentiate between different types of plants?

A photograph of a thistle before its bloom. The flower bud is surrounded by sharp thorn-like leaves.

Figure 1. Plant life on earth is diverse

Land plants evolved from a group of green algae, perhaps as early as 510 million years ago. The evolution of plants has resulted in widely varying levels of complexity, from the earliest algal mats, to bryophytes, lycopods, and ferns, to the complex gymnosperms and angiosperms of today. While many of the groups which appeared earlier continue to thrive, as exemplified by algal dominance in marine environments, more recently derived groups have also displaced previously ecologically dominant ones (for example, the ascendance of flowering plants over gymnosperms in terrestrial environments).

The establishment of a land-based flora led to an increased explosion of plant adaptations. To continue life within these new environments evolution was critical for success. Without the buoyancy of water they needed to develop structures to counteract gravity. As these plants spread further from water sources there was a need to better store resources and minimize water loss.

Plants also make our lives possible. Without the glucose they create through photosynthesis, and the oxygen they release into the air, it would be impossible for human life to continue on.

Learning Outcomes

  • Classify seedless plants
  • Classify seed plants