Sweet iris Iris pallida, the source of orris root used in perfumery. Flowering for the first time in the gardens at LPL HQ. The rhizomes are harvested after three years and then dried for up to five years and give off the aroma of violets. Perfumes that smell powdery contain orris root. The preparation of the root for perfumery is all done by hand and makes orris root one of the most expensive ingredients in fragrance-making.