Looks very much like the seed head of Nicandra physalodes, the Shoo Fly plant.
Sow the seeds as per the advice given for Allium seeds on here, somewhere!
Not grown it, but there is a huge patch of it a Chirk Castle in one of their Rock gardens. I get the impression from looking at it there that it does tend to spread.
Cutting the offended stem out would help, but Adam did sat=y he did not want to do that, so I did not offer that advice.
Another reason for disliking Roses!
Fairly normal for this cultivar at this time of year. Ours has had this every year for the last 20 years. It is now a very large tree. No treatment, but you could spray with a fungicide if you wanted to.
That is one severe infestation of scale insects. There are insecticides which will kill it. You need to get one which is based on Horticultural soft soap. The white covering is a waterproof wax which stops the insecticide from reaching the creature. The soap dissolves the wax and whammy!
It i9s not going to be a quick cure either.
Callicarpa bodinieri,. There are a lot of different species as well. Callicarpa americana and C. japonica are very similar to this one.
Looks like Arum maculatum. Very difficult to eradicate as the bulbs/tubers have lots of tiny offsets which soon grow. You can use Weed killer on them, Just add a little liquid soap to the mix, it makes it stick to the leaves.
Well, it spreads for us like Obelixx experienced. There is another one with slightly paler lemon coloured flowers which so far has remained a small clump. Helianthus giganteus 'Sheila's Sunshine'
T'other way round. C. tubulosa has been subsumed into heracleiefolia. However, if you wanted to buy it then it is still sold under the old name.
Our versions of C. heracleiefolia are much more purple than this one though.