Biodiversity or biological diversity is the sum of all the different species of animals, plants, fungi, and microbial organisms living on earth and the variety of habitats in which they live. Scientists estimate that upwards of 10 million - and some suggest more than 100 million - different species inhabit the earth. Each species is adapted to its unique niche in the environment.

The algae, fungi, mosses, lichens and liverworts, collectively known as lower plants, are the unsung heroes of natural history. Lower plants are at the heart of our life support system. Without lower plants, the rest of the living world couldn't function. We have left their existence to chance in the past but we now have to take positive action to conserve their diversity.

Keeping this in mind, this text includes 26 articles covering the diversity of algae, cyanobacteria, bacteria, pathogenic bacteria, fungi, lichens, bryophyte, and pteridophte. The contributors are internationally acknowledged experts in their field.