I'm conducting an analysis on plant and animal diversity in Europe. Can someone provide data (or clue, websites, references) on plant diversity in each country? Thanks!
The preceding answers relate to trees. For other plants such a public/open-access database for all countries does not exist to the best of my knowledge.
In case you want to build a plant species database yourself you may look for analogue lists like Conti's Checklist of the Italian vascular flora. The analogue/digital (Atlas) Flora Europea (AFE) got stuck decades ago, but preliminary studies have been published based on the incomplete AFE and give a reasonable first idea. Mountains & Med, or in other words altitudinal range and latitude (see attached).
In case your questions relates to a species-area releationship, just consider that over the cause of the last 200+ years, the area of almost all European countries changed substantially, in contrast to the number of plant species. Also, there will be some post-glacial artifacts in the data, in terms of number of tree species north and south of the Alpes.
It might be a better idea to look at US-States instead. They also have a much higher species number which is probably better when plotting the curve.