Janet Tweedy writes

Lesson learned by me of course that some plants are grafted even when
you don't think they are!

I had the same thing with a scented Viburnum - I think V carlessi. It
was grafted on to Wayfaring Tree (V lantana - thicker oval leaves) not V
opulus (guelder rose, thinner lobed leaves).

Lovely tree - I love the way the berries ripen at different stages so
that you have several colours at the same time (I was captivated by the
illustration in "Flower Fairies of the Autumn" when i was a very small
child), so I've had to wait till I was certain I'd got some cuttings
going successfully before getting rid of the suckers.
--
Kay