Yellow flag

Description

Iris pseudacorus, the yellow flag, yellow iris, or water flag, is a species of flowering plant in the family Iridaceae. It is native to Europe, western Asia and northwest Africa. Its specific epithet pseudacorus means "false acorus", referring to the similarity of its leaves to those of Acorus calamus (sweet flag), as they have a prominently veined mid-rib and sword-like shape. However, the two plants are not closely related. The flower is commonly attributed with the fleur-de-lis. This herbaceous flowering perennial plant grows to 100–150 cm (39–59 in), or a rare 2 m (6 ft 7 in) tall, with erect leaves up to 90 cm (35 in) long and 3 cm (1.2 in) broad. The flowers are bright yellow, 7–10 cm (2.8–3.9 in) across, with the typical iris form. The fruit is a dry capsule 4–7 cm (1.6–2.8 in) long, containing numerous pale brown seeds. I. pseudacorus grows best in very wet conditions, and is common in wetlands, where it tolerates submersion, low pH, and anoxic soils. The plant spreads quickly, by both rhizome and water-dispersed seed. It fills a similar niche to that of Typha and often grows with it, though usually in shallower water. While it is primarily an aquatic or marginal plant, the rhizomes can survive prolonged dry conditions. Large I. pseudacorus stands in western Scotland form a very important feeding and breeding habitat for the endangered corncrake. I. pseudacorus is one of two iris species native to the United Kingdom, the other being Iris foetidissima (stinking iris). Both the petals and stem are toxic to animals and plants. The plant was rated in second place for per day nectar production per flower in a UK plants survey conducted by the AgriLand project, which is supported by the UK Insect Pollinators Initiative. However, when number of flowers per floral unit, flower abundance, and phenology were taken into account, it dropped out of the top 10 for most nectar per unit cover per year, as did all plants that placed in the top ten, with the exception of common comfrey, Symphytum officinale.