A small genus of deciduous grasses, flat, upright leaves, which can be coloured and sometimes silvery spires of flowers. Distributed across the world, in warmer regions. Mostly grown in the UK is the Japanese blood grass, I. cylindrica and its forms.
Although a 'weed of concern' in some warmer parts of the world given its deep roots, spreading behaviour and ability to regrow from a mere fragment of rhizome, it has not yet spread outside of gardens in Britain, and indeed our climate is probably not conducive to its widespread naturalization.