as told to me - the flower referred to is more commonly known as Himalayan Balsam. But in the song and presumeably in Cornwall it has a colloquial name of "Beauty of Kashmir"

Look at the pictures and it does droop it's head at a certain time of the year as it goes to seed. The phrase "lay drooping it's head" is a specific date kind of referrence. Autumn - I would submit.

But I have no documentary evidence. I will ask Joy - the gardener - but she is no Folk scholar nor does she speak Kernak.