The aggregate of individuals that form geographically or ecologically dispersed populations that share morpho-physiological characteristics. In the natural environment, spores interbreed and inherit their traits and collectively occupy a continuous or partially discontinuous area. In the natural environment, species are segregated and are genetically stable systems. Most species are represented by morphologically distinct groups. The total number of species on Earth is estimated to be between 1.5 and 3 billion.

A species is a group of individuals that occupy a particular geographical area and have a number of hereditary characteristics that distinguish them from closely related species. Species that are similar in a number of ways are grouped into genera and these into families.