Sulphur yellow flowers, often with brown markings, appear from midsummer amongst the upright grey-green leaves of this vigorous water marginal. This native, evergreen yellow flag iris was once commonly found on marshy land and riversides and is ideal for planting at the margins of a large lake or pool. Iris pseudacorus also flourishes in deep, reliably moist soil that has been enriched with well-rotted organic matter. Great for wildlife and bog gardens, too.