Yellow Flag - Iris pseudacorus



"Yellow iris is an introduced invasive species that is native to Europe, western Asia and northwest Africa. Outside its native range, it is a significant invader in freshwater and brackish cattail marshes and spreads in marshes and adjacent areas by underground rhizomes and seeds. In North America, it is now found in many US states."(USDA)
"In BC, it is found in the southern part of the province, where it occurs in marshes, ditches, sloughs, streambank and pond edges. It is a favourite plant in water gardens and artificial ponds because of its bright yellow flowers." [E-flora]

Iris pseudacorus is a PERENNIAL growing to 1.5 m (5ft) by 2 m (6ft) at a medium rate.
It is hardy to zone (UK) 5 and is not frost tender. It is in flower from May to July. The flowers are hermaphrodite (have both male and female organs) and are pollinated by Bees, hoverflies.The plant is self-fertile.
Suitable for: light (sandy) and medium (loamy) soils. Suitable pH: acid, neutral and basic (alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers moist or wet soil and can grow in water. The plant can tolerates strong winds but not maritime exposure. [PFAF]


Edible Uses

See Hazards

Other Uses

The roots were once used like orris to scent linen closets. They are used also as a source of tannin and blue and black dyes. The flowers offer a yellow dye. [MPB-Duke]

Medicinal Uses


  • Analgesic (f; GMH); [MPB-Duke]
  • Analeptic (f; BOU); [MPB-Duke]
  • Antidote (f; BOU); [MPB-Duke]
  • Astringent (f; EFS); [MPB-Duke]
  • Carminative (f; EFS);[MPB-Duke]
  • Cercaricidal (1; X15880993); [MPB-Duke]
  • Diuretic (f; BOU; EFS; NAD); [MPB-Duke]
  • Emetic (f; EFS; HJP); [MPB-Duke]
  • Febrifuge (f; EFS);[MPB-Duke]
  • Insecticide (1; X15880993); [MPB-Duke]
  • Larvicide (1; X15880993); [MPB-Duke]
  • Laxative (f; EFS); [MPB-Duke]
  • Miracide (1; X15880993); [MPB-Duke]
  • Mosquitocide (1; X15880993); [MPB-Duke]
  • Purgative (f; BOU; HJP); [MPB-Duke]
  • Schistosomicide (1; X15880993);[MPB-Duke]
  • Sternutatory (f; EFS); [MPB-Duke]
  • Stimulant (f; NAD); [MPB-Duke]
  • Stomachic (f; EFS); [MPB-Duke]
  • Tonic (f; EFS); [MPB-Duke]
  • Vermifuge (f; EFS); [MPB-Duke]
  • Vulnerary (f; BIB). [MPB-Duke]



"Prefers a humus rich soil[79]. Succeeds in water up to 15cm deep[24]. Requires a moist soil, especially in early summer. Prefers a position in semi-shade[188]. Plants can be grown in quite coarse grass, which can be cut annually in the autumn[233]. A delicately scented essential oil is obtained from the dried roots[245]. Members of this genus are rarely if ever troubled by browsing deer or rabbits[233]. Some named forms have been selected for their ornamental value[187]. Special Features: Attractive foliage, Not North American native, Invasive, Naturalizing, All or parts of this plant are poisonous, Wetlands plant, Attracts butterflies, Suitable for cut flowers."[PFAF]


"Seed - best sown as soon as it is ripe in a cold frame[4]. Stored seed should be sown as early in the year as possible in a cold frame. A period of cold stratification improves germination time and rates. Prick out the seedlings into individual pots when they are large enough to handle and grow them on in the greenhouse or cold frame for their first year. Plant out into their permanent positions in late spring or early summer. Division in March or October. Early autumn is best[200]. Very easy, larger clumps can be replanted direct into their permanent positions, though it is best to pot up smaller clumps and grow them on in a cold frame until they are rooting well. Plant them out in the spring."[PFAF]

Uses of Iris Sp.

“Extracts of iris (Iris, lridaceae) rhizomes have a pungent and bitter taste. Tissue of the yellow flag iris, Iris pseudacorus, of Europe, is poisonous to man and animals, either fresh or dried, and produces unpleasant irritations of the mucous membranes, vomiting, and bloody diarrhea. Rhizoma iris was formerly a constituent of folk medicine and was considered a potent purgative. An essential oil is prepared from the roots of Iris pallida and I. germanica. After harvesting and sun-drying, the roots assume a pleasant violet-like scent which increases with time. The oil obtained by steam distillation is .'essence d'iris" or .'orris root oiL" The odoriferous principle is called "irone." Three isomers are the major component of this essential oil (Fig. 23.28). In contrast to the ionones that are widespread in nature, irones are found primarily in orris root oil. Freshly harvested rhizomes do not contain irones; the scent develops gradually over 3-4 years of storage of the root stocks. It seems unlikely that irones arise by enzymatic processes; oxidizing agents accelerate formation of these compounds. “ [Seiger PSM]


Page last modified on Sunday, January 21, 2018 1:17 PM