I do not know the european name for the buttonwood..
Theo,
it is platanus occidentalis ( platano americano)

A common error. This is why we have botanical names. I was referring to Florida
buttonwood, Conocarpus erectus. It is God's gift to American bonsai, equal to
anything the mountains of China or Japan can produce. Sadly, it is little known
in Europe, although it would probably be easy to grow in the Mediterranean
countries. The problem is that you can't grow one from seed or cuttings, since
its whole appeal is the deadwood. They are collected, which makes them very
expensive.
Actually, Platanus occidentalis, which we call sycamore, is not particularly
suited for bonsai. The leaves are way too big.
Iris,
Central NY, Zone 5a, Sunset Zone 40
"When you come to a fork in the road, take it." Yogi Berra