Endangered species make up a large proportion of our flora. For this reason, SKEW had to set priorities in species conservation from the very start and concentrate on species needing very urgent conservation measures and species of international importance.

In 1992, SKEW defined a first priority list with about 40 plant species occurring in Switzerland, endangered or rare throughout Europe.

In 1997, a group of experts from SKEW/ZDSF added further endangered species to this list, making an integral list of about 700 priority plant species for Switzerland. Until now detailed field research has been carried out for 142 species (see data sheets).

Currently, the whole list is being revised in a mandate from SAEFL (since 01.01.2006: Federal Office for the Environment FOEN); it includes:

- Red List 2002, which used the new international endangerment categories from IUCN

- New criteria for determining the international responsibility for a species (area proportion, degree of endemism)

- Feasibility (species for which measures can be taken)