Stinking Iris

Wiki - It is one of two iris species native to Britain, the other being the Yellow iris (Iris pseudacorus). Its flowers are usually of a dull, leaden-blue colour, or dull buff-yellow tinged with blue; the capsules, which remain attached to the plant throughout the winter, are 5-8 cm long; and the seeds scarlet.

It is known as "stinking" because some people find the smell of its leaves unpleasant when crushed or bruised, an odour that has been described as "beefy".