That would be really modern and such a beautiful reflection of their future as the King and Queen of not only GB but the the commonwealth. I have a feeling we will see roses, lillies and such like all other British royal brides, but one can hope. Here are the national floral emblems of the commonwealth realms
antigua and barbuda: dagger log
http://pottersprimaryschoolanu.wiki...er.jpg/174249647/Antigua%20Nationalflower.jpg
australia: eucalyptus
http://3.bp.blogspot.com/_8fdAjWGnO...wACGPI/s1600/Eucalyptus+ficifolia+flowers.jpg
Bahamas: the yellow elder
http://www.reefnews.com/reefnews/news/v04n06/ylweldr2.jpg
Barbados: the pride of Barbados
http://image03.webshots.com/3/7/81/86/16778186ZmvnbQxijy_ph.jpg
Belize: black orchid
http://image03.webshots.com/3/2/16/97/20421697YNveCKgIUO_ph.jpg
Canada: unfortunately the maple leaf might look a bit odd but we could look to a provincial flower
Alberta wild rose
http://healthytastebuds.files.wordpress.com/2010/03/pink-wild-rose.png
Saskatchewan: tiger lily
http://www.thesnozberries.com/Tiger lily jpg.jpg
grenada doesn't have one I can find
Jamaica:Lignum vitae
http://gqrentalstours.com/img/flower2.JPG
New Zealand: like canada is foliage, but the silver fern would look less out of place than a maple leaf
http://noyfamily.com/nz/nelson/160_6073_std.jpg
Papua New Guinea
No official flower like Grenada
Saint Kitts and Nevis: red royal poinciana
File:Flamboyant BW 2.jpg - Wikipedia, the free encyclopedia
St Lucia seems to be the rose called the marguerite
FLOWER* FESTIVALS
St Vincent is the soufriere tree:
http://www.guadeloupe-bonheur.com/en-activities3.jpg
solomon islands has none I can find nor Tuvalu so of 15 commonwealth
Solomon, Tuvalu, Papua New Guinea and Grenada have none that leaves 11
Then we also have the flowers for the United Kingdom
England: the tudor rose (red rose)
http://www.mzephotos.com/images/roses/red-rose.jpg
Scotland:
the thistle:
http://www.types-of-flowers.org/pictures/thistle.jpg
blue bell
http://www.fabiovisentin.com/photography/photo/13/blue-bell-flower-campanula-dsc01879.jpg
or heather
http://www.yorkshiremoors.co.uk/pics/pics/heather5.jpg
Northern Ireland
the shamrock: could be cute to include one for good luck
orange lily
http://image03.webshots.com/3/8/58/11/2085811UqHdWjlZBS_ph.jpg
or flax
http://upload.wikimedia.org/wikipedia/commons/6/6b/Flax_flowers.jpg
Wales:
daffodil
http://www.edwud.com/photos/wild_daffodil_flowers_durham_england.jpg
leek
http://ircyber.persiangig.com/image/leekflowermain.jpg
Even if they didn't want to go too exotic, picking flowers from among the symbols of the UK, would be colorful and different as well.
I just hope if they go for the traditional, we see something like fire and ice roses, or colored lilies, something to stand out.