Thanks Ivo, it is a lovely set and I am relieved it is still together, especially as I might well have split it up.
Last week I was flicking through a friends copy of the book Venetian Glass in the 1890s: Salviati at Stanford University by Carol M Osbourne, that is where I saw a photo of one of these trees. I will take another look at that book and check that they really do match. Both the yellow and green colours are achieved with frit (pulveri) on clear glass and it all matches, which is one of the reasons I am confident they belong together. The orange glass matches nicely too.
Another group photo: