A good find Eric, and thanks for posting it here.
From the About page on the website:
The Plant List is a working list of all known plant species. Version 1, released in December 2010, aims to be comprehensive for species of Vascular plant (flowering plants, conifers, ferns and their allies) and of Bryophytes (mosses and liverworts). It does not include algae or fungi. Version 1 contains 1,244,871 million scientific plant names of which 298,900 are accepted species names. It includes no vernacular or common plant names.
Collaboration between the Royal Botanic Gardens, Kew and Missouri Botanical Garden enabled the creation of The Plant List by combining multiple checklist datasets held by these institutions and other collaborators.
The Plant List provides the Accepted Latin name for most species, with links to all Synonyms by which that species has been known. It also includes Unresolved names for which the contributing data sources did not contain sufficient evidence to decide whether they were Accepted or Synonyms.
That source is perfect for verifying the names of plants for entry to Ideas Genie
Its particularly useful as it lists the synonyms, so again we can be sure we are using the latest flavour of plant name when we add plants to our Ideas Genie databases.
1,244,871 million scientific plant names. Gosh
The Master Database for use with Ideas Genie currently has a mere 36,000 plants