A plant that parasaitizes trees could only be in the family Viscaceae or Loranthaceae I think

and this does not look like these at all.
I think it's a shrub growing close to the tree, looks broom-like or Gnidia-like. And there are pods if I am not mistaken.
I'm gonna hazard a guess and say it's not a Scotch broom (invasive)
Cytisus scoparius
but might be a scrambling shrub in the Capparaceae family such as
Cadaba aphylla (looks very much like yours, but not very common in the north-east)
