Irish linen is an exclusive linen fabric that has been produced in Ireland for several centuries. Just like any linen, Irish linen is woven from yarn made out of fax - a plant also know as linseed. Until the turn of the century most of the flax naturally grew in Ireland, but later on advanced agricultural methods eventually led to flax production all over northern Europe. France, Belgium and the Netherlands had the largest production of flax.
The flax doesn't have to be grown in Ireland to label the finished fabric "Irish Linen". To pass as genuine Irish linen the fabric only has to be woven in Ireland, and even the yarn can be imported. Today most of the Linen production has moved to China, and the small portion of Irish Linen that is still being produced is usually tailored to the top end of the market.