Tulips are hardy bulbous perennial herbs with mostly basal, straplike leaves. The flowers are usually cup or bowl shaped and usually have six tepals. The name tulip is derived from the Persian word toliban meaning turban, which is an apt term to describe the flower shape of certain tulips. However, there are tulips with star shaped flowers, double flowers, and tulips with tepals that are reflexed, elongated, or fringed. Most tulips produce a single flower on a central stem, but some species bear multiple flowers. Most tulips bloom in the spring. Tulips have been developed in nearly every color except true blue. There are around 100 species, originating from the region from southern Europe, north Africa, and Asia from Anatolia and Iran east as far as northeast China and Japan. Tulips cannot be grown in the open in tropical climates, as they require a cold winter season to grow successfully. The tulip is the national flower of Iran and Turkey, and tulip motifs feature prominently in Persian and Turkish folk arts. The European name for the flower is a misuse of the Persian word for turban, a mistake probably originating in the common Turkish custom of wearing flowers in the folds of the turban.