Mainly the pinetrees in the winter landscapes...
http://www.photon-interactive.de/City-Bus/City-Bus%202007-12-10%2017-53-08-12.jpg
...and some of the smaler plants in the gardens.

It's really important to respect the licence agreements when using other peoples artwork. Such lack of proffesionality can easily lead to loss of publishing partners if one has to take legal actions.