There is often confusion when trying to distinguish British native bluebells (Hyacinthoides non-scripta) from introduced Spanish bluebells (H. hispanica) and hybrids between the two (H. x massartiana).
English bluebell
Flowers of native bluebells are narrowly bell-shaped, with straight-sided petals, deeply curled back at the tips. The majority of flowers droop from one side of the stem. The anthers are creamy-white and the leaves narrow, usually between 7-15mm wide (although occasionally up to 20mm).
Spanish bluebell and hybrid
The bell-shaped flowers of Spanish bluebells and hybrids open more widely than on English bluebells, with the petal tips just flaring outwards or curling back only slightly. Some flowers may droop from one side, but most are arranged all around the stem and held more erect. The anthers of Spanish and hybrid bluebells are usually pale to dark blue, and the leaves are wider, up to 30-35mm across.
Controlling spread
Bluebells are fairly resistant to most weedkillers. Dig out unwanted plants when in leaf: this makes it easier to lift as many bulbs and runners as possible. Dispose of carefully: never discard garden-plant material in the countryside.
Dawn Edwards