It is not always easy to distinguish between bluebell species. There is variation within the one species, the size of the plant depends on seasonal conditions, and perennial species die off in hot summers, so that it can be difficult to decide whether the plant is an annual or not. Tall Bluebell (Wahlenbegia stricta) is by far the most common. Annual Bluebell (Wahlenbergia gracilenta) is moderately common. It is much smaller than Tall Bluebell.
Wahlenbergia - named in honour of the Swiss Botanist Goran Wahlenberg born 1780.