We have a tree in our garden in the Haut Vienne, France.It is about 12 feet tall(4 metres) and been established for several years. In the summer it has large heart shaped leaves (1ft/30cm x 8in/20cm) and last autumn when it shed it's leaves it left upright clusters of what looked like brown suede textured "nuts". But now, 1st May, these "nuts" are coming into flower! Large, purple/blue trumpet shaped flowers, one from each "nut" obviously buds. One other characteristic of the tree is the branches are tubular, only visible when pruned. Help what is this tree?