Known as the bamboo iris, this has fan like leaves and long stems with swollen nodes.  The charmingly pretty pale blue flowers are borne in late spring and the whole plant has a will of its own, wandering among others and sometimes rooting where the nodes touch the ground.  Others describe it as 'upright' or 'compact' which is not our experience!  It's quite unusual and something of a plantsman's plant. Grow in a sunny spot which is well drained, such as the edge of a walled bed.  Here, it has gone -7C in our garden. 3 litre pot.