I read here: http://acornergarden.blogspot.com/2009/02/making-commitment-to-signature-plant.html about the idea of a signature plant. I think it's meant to be taken as something you adopt and show great love and effort with. In our garden it couldn't really be anything other than the apple trees. When we moved here, they adopted us. We have 3 mature ones: a bramley, a russet, and another which gets very red. They are at least 50 years old, since our next-door neighbour remembers them that long, and I susepct a good deal older. We also have a dwarf one and another youngster.
They blossom in the first to second week of May, and the fruit ripens in September. We have an apple press (a wonderful birthday present to me from my husband about 5 years ago) and we make cider and apple juice (since I don't drink alcohol).
I will post some photographs here of the trees when they are blossoming.
The trees mean a huge amount to me. They seem to own the garden far more than we do. I love their presence through the winter, and their ever-changing nature. They're always there and never the same.