Fortunately most of the local bluebells are the native English bluebells (Hyacinthoides non-scripta) but when I was south I noticed some Spanish bluebells (Hyacinthoides hispanica) at the bottom of the garden.   I was surprised to see some which looked as if all the florets were grouped into a ball shape  and perhaps someone might be able to tell me why this is so. 
In the vase the three drooping stems with the narrow bells are English bluebells whereas the others are the Spanish bluebells with straight stems and wider bells all round the stem.    Although Spanish bluebells are attractive there is a great danger that because they are more vigorous they will hybridise and eventually there will be fewer woods of the native scented bluebells.