The principal group studying Devon's flora is the Devonshire Association's Botany Section. Founded over 100 years ago, the Section organises around a dozen field meetings a year throughout the county. You can find a brief summary of these meetings on the Devonshire Association's website, or for the full programme contact the secretary, Tim Purches.
The Section's interests are not confined to the higher plants, but also cover bryophytes (working with the Devon Bryophyte Group), lichens and fungi (working with the Devon Fungus Group). Much effort in recent years has been put into producing a new Flora for Devon, which should be available in the near future.