Hi Johanna,
Can you provide a link to it? When I search for Gaura Grace, all I get is this:
http://www.kew.org/search/sear...
which isn't a reference to a cultivar of Gaura lindheimeri called 'Grace', but rather just mentions "grace-ful" flowers and Gaura lindheimeri in the same paragraph?
Also, as Evan mentioned above, the currently accepted name of these plants is Oenothera lindheimeri. However, if you search for Gaura lindheimeri in the ATP database, they will still all show up:
http://garden.org/plants/searc...
Thanks,
Kent