A list of the 800 most important sites for wild plants in central and Eastern Europe has been published by the charity, Plantlife International.
The report identifies sites of exceptional botanical richness
Many of the sites contain endangered species and yet a fifth have no legal protection, the group warns.
Agriculture, forestry and tourism are the main threats to "Europe's last areas of wilderness", its report says.
If they cannot be saved "we risk a spiritual impoverishment such as no generation has known before", it adds.
Hundreds of specialists from academic institutions and non-governmental organisations identified the best sites for wild plants, fungi and their habitats in seven countries.
They were Belarus, the Czech Republic, Estonia, Poland, Romania, Slovakia and Slovenia.
The report also looked at the threats to each internationally important site for wild plants (IPA).
It found that:
Other threats include development, urban and transport, and invasive plant species.
- Poor forestry practices threaten 44% of IPAs
- Tourism threatens 38%
- Agricultural intensification (grazing, hay-making, arable) threatens 29%.
Plantlife International wants all IPAs to be recognised as priority sites for conservation.
Ancient "virgin" forests need better management
"This is the first time that we've ever had this kind of comprehensive survey," Elizabeth Radford told the BBC News website.
"We want people to visit these sites but it has got to be managed sensibly and carefully."
Parallel projects in south-eastern Europe and in Russia are also under development. The list of IPAs in the UK will be published early next year.