ID Please.. Strange Plant

In my Dad's garden there is a couple of plants growing at the side of the fence that he was concerned about. He initially thought it was Japanese Knotweed and the top leaves do look like Japweed but it definitely isn't as they don't form that criss-cross/staggered pattern of leaves and the stems are purely green, and the leaves grow equally on both side of the branches.

However, at the base, the leaves have turned somewhat spiky-looking, kind of akin to Hogweed/Cow Parsnips but finer leaves, like Wolvesbane.

I will take some pics tomorrow and try to upload them with my new phone (which may take some figuring out though).

If anybody has any ideas in the meantime, it would be appreciated as I'm stumped on this one as the plants have incredibly variated foliage from spade/heart shaped leaves at the top and spiky-looking ones at the bottom and are about 4ft tall with no sign of flowers forming yet.

 

Excellent! You'll stand a greater chance of a more accurate ID

 

Japanese Knotweed. The branches have a slight zig-zag to them Mowerman.

 

Definitely Japanese Knotweed. There are strict rules about getting rid of it, so be warned.

 

Are you referring to Sheal's picture Dai.
Or just have a fantastic imagination?

 

There are actually laws about getting rid of Knotweed, Pete.

 

I didn't say there wasn't.

I'm just wondering how you made the definite ID from the OP?

 

Try telling that to my Government here Dai. The picture I took above is in a coastal position in a glen. The banks there are smothered in it, stretching to about 100 yards and 30/40ft high on one of the banks.

 

Shiney, this is a notifiable plant and illegal to let it grow.

 

They are probably aware of it but don't want the expense of controlling/killing it!

 

Thanks guys and @Sheal. I know Japweed very well and agree with your desctiption about the zig-zag branches and this is definitely not the 'dreaded one'. It may just be a plant that was given to my dad as he has planted so many, he's kind of lost track of what is what. But it could be a weed that I've never seen before. We're both at a loss, although he has a suspicion it may be Himalayan Honeysuckle.

Here are some pics of the plants as promised. The bottom leaves seem to have filled out over the last few days and are thicker than Delphiniums or Wolfsbanve, more like hogweed in shape but much thinner in depth and rather delicate.

It just baffles me with the top leaves are so incredibly different to the bottom ones. The stems are also very delicate and incredbibly hollow inside with a very thin outer stem wall thickness.

If my Dad's suspicions are accurate, this could turn out to be a problem if left to seed. Would be interesting to see what it looks like when/if it flowers this year.

 

Its Leycesteria formosa.
Its a nice shrub in the right place.