I would like to download a plant database containing photos and species details. Do you know if there are any openly available online?
Large online floras have the advantage of not only having details and often photographs and illustrations, but also being (more or less) definitive, that is, botanists will refer to them.
See my answer here for links to examples, and also for some of the problems with using floras (e.g. not easily downloadable).
1. DELTA identification program key. (DELTA – DEscription Language for TAxonomy).
https://florabase.dpaw.wa.gov.au/ (Australian Database).
3. Royal Botanic Garden (England) and Kew Herbarium 's Database.
4. Actkey, maintained by Harvard University Herbarium
5. Taxacom, an E-mail server for discussion on systematics of living-systems. Monitored by University of Kansas
http://mailman.nhm.ku.edu/cgi-bin/mailman/listinfo/taxacom (Taxacom main page)
http://mailman.nhm.ku.edu/pipermail/taxacom/ (Taxacom Archive)
http://taxacom.markmail.org/ (Post- Search engine)
6. Angiosperm Phylogeny Website, under Missouri Botanic Garden.
Source: Plant Systematics- Theory and Practice, 2nd Edition, by Gurcharan Singh, Oxford and IBH Publishing House New Delhi
The United States Department of Agriculture have a plant database (http://plants.usda.gov) where you can download search results and checklists. Look at their download page. However, I think that you can only download text (no pics), and it mostly (only?) contain plants found in the US. I have not used the download functionality myself, so I do not know anything about flexibility or interface.