Easy plant identification with images:
https://plantsam.com
Plant and animal identification with over 1,800 plant species.
Plant names, genus’ and species lists
https://www.ars-grin.gov
KEW checklist of selected plant names
Regional
https://ispot.org.za (South Africa) shows plants in their natural habitat.
Cacti and other succulents
http://www.cactusinhabitat.org
https://bellepiante.it/piante-succulente/
http://cactiguide.com