The leaves and stem look to me like Nerium oleander but I haven't got a picture of any fruit so I can't be sure.

It might well be Oleander the leaves are very similiar and I think they may be used to add to a bunch of flowers to add decoration.

Thank you

Hope

I agree it does look like Nerium, but if those round berry type seed cases are attached to that stem, it can't be Nerium - the seed cases it produces are nothing like that. MIght help to see a photo of just that single stem on its own, out of the vase.

It looks like either a Pistache, or possibly a Sumac, judging by the leaf shape, leaf attachment, and the fruiting stem.