Looks like I must inspect the plant again next time I visit the forest 
Back to the VM plant - could it be a kind of Rubus?
It wouldn't come to my mind at first, but there are a couple of indications:
- Rubus needs human intervention if you want it to climb. It needs to be attached to a support. This might explain the remarkable way the "vines" intersect with the stem. Note that we don't know the scale of the support - it might represent a tree, but the arrangement of the leaves indicates it's young growth.
- It's possible that the "berry clusters" in the VM are meant to represent the "bulbs" on some Rubus fruits, rather than individual berries.
- More so than with ivy, the berries may appear on sections of the plant that look leafless. However the species I know only start shedding their leaves when the berries have passed their expiration date...
Ivy top, blackberry bottom:
But as Wladimir notes, Dioscorea (like black bryony) does keep its berries after shedding the leaves. They aren't edible though, so I don't understand why they would be depicted in such a fashion...
On the other hand, I might add, there are hundreds of Rubus species, too many to check. If it were something common like blackberry it may have been portrayed differently.
Back to the VM plant - could it be a kind of Rubus?
It wouldn't come to my mind at first, but there are a couple of indications:
- Rubus needs human intervention if you want it to climb. It needs to be attached to a support. This might explain the remarkable way the "vines" intersect with the stem. Note that we don't know the scale of the support - it might represent a tree, but the arrangement of the leaves indicates it's young growth.
- It's possible that the "berry clusters" in the VM are meant to represent the "bulbs" on some Rubus fruits, rather than individual berries.
- More so than with ivy, the berries may appear on sections of the plant that look leafless. However the species I know only start shedding their leaves when the berries have passed their expiration date...
Ivy top, blackberry bottom:
But as Wladimir notes, Dioscorea (like black bryony) does keep its berries after shedding the leaves. They aren't edible though, so I don't understand why they would be depicted in such a fashion...
On the other hand, I might add, there are hundreds of Rubus species, too many to check. If it were something common like blackberry it may have been portrayed differently.