Koen, are you saying that sprouted branch on the right is growing from the dead-looking (and very old) vine hanging from the birch?
If it's part of the vine, I think we can rule out clematis (some species have similar leaves but they don't usually get huge), swallow-wort, and lonicera (wrong veins) and jasmine (wrong leaf arrangement). It's much too big for anything in the pea or Hypericum family and I don't think catchfly could ever grow that big (although the leaves are similar to spring catchfly). Paederia doesn't usually get that thick.
Wisteria can get huge, but the leaves are odd-pinnate.
If it's an import, some of the South American creepers can get pretty big. Unfortunately, I'm not as familiar with South American plants.
The leaves are somewhat similar to the Asian Lonicera but even the Asian varieties don't typically grow that big unless they are rain-forest plants. Too bad there are no flowers or buds yet. That would help a lot!
If it's part of the vine, I think we can rule out clematis (some species have similar leaves but they don't usually get huge), swallow-wort, and lonicera (wrong veins) and jasmine (wrong leaf arrangement). It's much too big for anything in the pea or Hypericum family and I don't think catchfly could ever grow that big (although the leaves are similar to spring catchfly). Paederia doesn't usually get that thick.
Wisteria can get huge, but the leaves are odd-pinnate.
If it's an import, some of the South American creepers can get pretty big. Unfortunately, I'm not as familiar with South American plants.
The leaves are somewhat similar to the Asian Lonicera but even the Asian varieties don't typically grow that big unless they are rain-forest plants. Too bad there are no flowers or buds yet. That would help a lot!