http://plantaardigheden.nl/plant/beschr/default.htm
Good site for dutchies, interested in plants.
It's possible to do a search / click a plant and see it's description, uses, folklore, habitat, etc.
It even has a section with an old scanned herb book (1554)!!
And a Wiki:
http://nl.wikipedia.org/wiki/Angiosperm_Phylogeny_Group
Not very much info, but it contains pictures - and can even be viewed if you don't understand dutch (it's mostly latin on the first page, which I don't understand - but can manage by clicking away
)
If you alter the "nl" part in the URL for "en" you'll find the english version of the page ... containing even less info
EDIT:
Angiosperm Phylogeny Group website:
http://www.mobot.org/MOBOT/research/APweb/welcome.html
a wee bit scientific, but good info on classification etc.
Contains maps with spreading details in the world.
Tree identification:
http://www.bomengids.nl/hoofdsleutel.html (in dutch)
http://www.bomengids.nl/uk/hoofdsleutel.html (in english)
EDIT 2 (20 Feb.):
http://www.reticule.co.uk/flora/
Possibility to ID a plant, also have a look in the link section en recommended booksection (links to Amazon, regarding good plant books - including 2 Flora's of the British Isles).