Could anyone help me identify this plant please?
It was found growing in the UK this May on a building site.
Stem - similar to flag iris.
Leaves - coming from the stem, similar to iris but finer.
Flower stalks coming from the leaf axils.
Flowers - blueish, 18-20 petals, daisy-like, about2.5 inches across.
brownish centre with gold-tipped stamens.
Root - white carrot-shaped.
Height of plant above ground - about 30 inches.
Thanks a lot - Andy Meek, Derby, England