What is the ‘representative number of species’ concept in written description?

This page is an FAQ based on guidance from the Manual of Patent Examining Procedure. It is provided as guidance, with links to the ground truth sources. This is information only: it is not legal advice.

The ‘representative number of species’ concept is crucial in demonstrating adequate written description for a claimed genus. The MPEP explains:

“A “representative number of species” means that the species which are adequately described are representative of the entire genus. Thus, when there is substantial variation within the genus, one must describe a sufficient variety of species to reflect the variation within the genus.”

This is particularly important in unpredictable arts or when claiming a broad genus. A single species may not be sufficient to support claims to a broad genus if there is substantial variation within that genus. The number of species required depends on the particular invention, the size of the genus, and the level of skill and knowledge in the art.