Aggregate species consist of a a group of taxa, usually lower taxa such as subspecies and varieties.
An example is Sanguisorba minor. This species includes three subspecies, subsp. minor, subsp. muricata and subsp. magnolii.
All three are displayed on the genus Sanguisorba page. The aggregate species is indicated by the blue Agg. code
The reason for introducing the concept is that many records, by us and others, are to species level only. In these cases, we don't know to which subspecies the record belongs. However, we can still use them at the aggregate species level. Each of the subspecies also has its own page with information and records.