''Physcomitrella'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

moss Mosses are small, non-vascular plant, non-vascular flowerless plants in the taxonomic phylum, division Bryophyta (, ) ''sensu stricto''. Bryophyta (''sensu lato'', Wilhelm Philippe Schimper, Schimp. 1879) may also refer to the parent group bryo ...

es, containing two species. ''

Physcomitrella patens ''Physcomitrella patens'' is a synonym of ''Physcomitrium patens'', the spreading earthmoss. It is a moss, a bryophyte used as a model organism for studies on plant evolution, development, and physiology. Distribution and ecology ''Physcomitr ...

'' is a

model organism A model organism is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workings of other organisms. Mo ...

in laboratory research. '' Physcomitrella readeri'' is fairly similar, distinguished only by subtle characteristics. In fact, it has often been debated whether they should rightly be considered separate species, or a single species. ''Physcomitrella'' has been used as a

. It diverged from the

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...

s over 400 million years ago, so the difference between the groups indicates the changes in the

genome A genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding genes, other functional regions of the genome such as ...

that accompanied the adaptation of plants to living on land.

References

Moss genera Funariales {{Bryopsida-stub