This section is from the book "British Wild Flowers - In Their Natural Haunts Vol2-4", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
This marsh plant is found in the Neolithic deposits at Crossness, and Fife. To-day it is found in Europe, N. Africa, and Siberia in the N. Temperate Zone. In Great Britain the Yellow Flag is universally distributed. It is also found in Ireland.
One of the most distinctive components of the marginal vegetation of watery places is this plant, which is common in every habitat where aquatic conditions are continuous and marked. It is a denizen of ponds, pools, and lakes. It is to be found by the side of every stream and river, often in ditches, and it invades the wider areas of marsh and bog-land, growing in the reed swamp.
This is a tall plant, with leaves all or mainly radical, adopting the grass habit. The plant has the flag habit. The rootstock is acrid, stout, and creeping. The stem is round in section. The leaves are flat, long, broad, sword-shaped, mainly radical, equitant.
The scapes are leafy, sometimes branched above. The flowers are deep-yellow. The ultimate flower-stalks are as long as the ovary. The petals are spoon-shaped, shorter than the sepals, 3, erect, the latter being petaloid and purple-veined, with an orange spot near the base. The 3 outer perianth-segments are of clear yellow, large and spreading, bent back, the blade broadly inversely egg-shaped, the claw rather short. The tube is cylindrical. The stigmas are long and narrow, longer than the petals, yellow. The capsule is leathery, 3-angled, 3-ribbed, the seeds numerous, vertically flattened, with flat faces, with a hard testa.
The Yellow Flag is 3 ft. high. Flowers are found in June. This beautiful plant is a perennial deciduous herbaceous plant, propagated by division of the rhizome. It is quite worthy of a place in our gardens.
The flowers are honeyed. The outer perianth is petaloid, in 6 parts (2 sets of 3 segments), with sepals taking the place of petals, bending down at the outer ends. The styles are petaloid with broad appendages, and opposite them and below are the 3 stamens, which are inserted at the base, with free anther-stalks, and basifixed anthers which open externally. The flowers are large and conspicuous, the stigmas arching over the stamens. The petaloid sepals and golden stigmas, also petaloid, render the flowers conspicuous. The honey is secreted at the base of the flower. The style is opposite the anthers and large, with 3 large, flat branches, the appendages resembling a petal, which arch over the anthers and outer perianth-segment.
Photo. L. R. J. Horn - Yellow Flag (Iris Pseudacorus, L.)
The stigma forms a flap on the outer side, just over the anther, with a point below the stigmatic lamella. An insect seeking honey pushes its way between the outer perianth-segments and the style, the anther being between. It must rub its back against the anther, which opens outwards. In returning from its honey quest it does not touch the stigmatic surface of the stigma which is above, but does this on entering already dusted with pollen from a previous flower.
The Yellow Flag is visited by Bombus, Osmia, Honey-bees, and a fly, Rhingia rostrata.
The capsule opens above, and allows the smooth flattened seeds, when blown by the wind, to fall some distance away.
Yellow Flag is a peat-loving plant, growing in a peat soil, or pelophilous on a clay soil.
The fungi Puccinia iridis, Uredo iridis, attack the Yellow Flag. Several beetles are found on it, Aphthona non-striata, A. ponderosa, Mononychus, and two Lepidoptera, the Crescent (Apamea fibrosa), the Double-lobed (A. ophiogramma).
Iris, Theophrastus, is the Greek for rainbow. Pseudacorus, Linnaeus, is Greek for false acorus, Acorus being the generic name of the Sweet Flag or Galingale.
There are many English names, e.g. Butter-and-Eggs, Cegge,
Cheiper, Cucumbers, Daggers, Dragon-flower, Flag, Water or Yellow
Flag, Flaggan, Flagons, Fliggers, Yellow Flower-de-luce, Jacob's
Sword, Laister, Laver, Levers, Livers, Lug, Maiken, Meklin, Yellow
Saggan, Sedge, Seag, Seggs, Water Seg, Seggin, Shakier, Skeg,
Sword Flag, Water Lily. It is called Cheiper, "because children make a shrill noise with its leaves". The name Cucumbers refers to the seed-vessels, which when green resemble young cucumbers.
Fliggers was applied to it from the motion of its leaves by the slightest impulse of the air. As to the name Flower-de-luce, Shakespeare writes:"Awake, awake, English nobility! Let not sloth dim your honours new-begot. Cropp'd are the flower-de-luces in your arms; Of England's coat one half is cut away."
Spenser also includes it:"Show me the grounde with daffadowndillies And cowslips, and kingcups, and loved lillies, The pretie pawnce And the chevisaunce Shall march with the fayre flowre delice".
When chopped up and chewed, the root was considered a cure for toothache. In Chaucer's day it was called Gladdon or Gladyne, and an antidote for poison. The seeds have been used as coffee. The root powdered was used also as snuff. The plant is astringent, and has been used for ink and dye of a black colour. The juice of the root is cathartic, and has been used for dropsy.
Essential Specific Characters:296. Iris Pseudacorus, L. - Stem round, leafy, leaves ensiform, flowers yellow, stigmas longer than the perianth, which is beardless.