For every one of us, as well as for each community in various parts of the world, feelings and memories of Christmas-past are triggered by associated images of other remembered seasons in our landscape. The universal floral symbol of Christmas is the poinsettia (originally Mexican) which can also be found here as an import to Sydney, though not in great abundance.
With no "white Christmas" for your average Aussie, it's the Christmas bush (Ceratopetalum gummiferum) that tells Australians tis the season to be jolly. The Christmas bush grows just about everywhere, brightening the landscape with its coppery red sepals tinged with tiny white petals. Aussies have been gathering these Christmas bush branches to mark the season as far back as 1882. Cut flowers are now exported to Japan for the Japanese to welcome the New Year.
My favorite tree, one I personally link with Christmas in Sydney, is the Kurrajong or Illawarra Flame tree (Brachychiton acerifolius) which is a native of the east coast of Australia. Unlike the spreading poinciana flame tree it has bell shaped flowers and really looks spectacular at this time of the year.