Daniel Mosquin posted a link to this document in a Botany Photo of the Day posting, and I thought it was worth saving in this forum. On The Use Of The Terms Subspecies And Variety It's a long read. Daniel also quoted the definition from the USDA’s National Plant Materials Program Manual (4th ed.): The terms “subspecies” and “variety” are used to designate the first and second divisions of a species. A “subspecies” is a grouping within a species used to describe geographically isolated variants, a category above “variety”, and is indicated by the abbreviation “subsp.” in the scientific name. A “variety” consists of more or less recognizable entities within species that are not genetically isolated from each other, below the level of subspecies, and are indicated by the abbreviation “var.” in the scientific name.