Spanish iris being the earlier of the two. Bulbing reticulate iris (subgenus Hermodactyloides) Reticulate irises with their characteristic bulbs, including the yellow I. danfordiae, and the various blue-purple I. histrioides and I. reticulata, flower as early as February and March. These reticulate-bulbed irises are miniatures and popular spring bulbs, being one of the first to bloom in the garden. Many of the smaller species of bulbous iris, being liable to perish from excess of moisture, should have a well-drained bed of good but porous soil made up for them, in some sunny spot, and in winter should be protected by a covering of half-decayed leaves or fresh coco-fiber. Gallery Uses Aromatic rhizomes Rhizomes of the German iris (I. germanica) and sweet iris (I. pallida) are traded as orris root and are used in perfume and medicine, though more common in ancient times than today. Today Iris essential oil (absolute) from flowers are sometimes used in aromatherapy as sedative medicines. The dried rhizomes are also given whole to babies to help in teething. Gin brands such as Bombay Sapphire and Magellan Gin use orris root and sometimes iris flowers for flavor and color. For orris root production, iris rhizomes are harvested, dried, and aged for up to 5 years. In this time, the fats and oils inside the roots undergo degradation and oxidation, which produces many fragrant compounds that are valuable in perfumery. The scent is said to be similar to violets. The aged rhizomes are steam-distilled which produces a thick oily compound, known in the perfume industry as "iris butter" or orris oil. Iris rhizomes also contain notable amounts of terpenes, and organic acids such as ascorbic acid, myristic acid, tridecylenic acid and undecylenic acid. Iris rhizomes can be toxic. Larger blue flag (I. versicolor) and other species often grown in gardens and widely hybridized contain elevated amounts of the toxic glycoside iridin. These rhizomes can cause nausea, vomiting, diarrhea, and/or skin irritation, but poisonings are not normally fatal. Irises should only be used medicinally under professional guidance. Water purification In water purification, yellow iris (I. pseudacorus) is often used. The roots are usually planted in a substrate (e.g. lava-stone) in a reedbed-setup. The roots then improve water quality by consuming nutrient pollutants, such as from agricultural runoff. This highly aggressive grower is now considered a noxious weed and prohibited in some states of the US where it is found