The 15-20 species of the genus Hemerocallis originate from temperate Asia. They are herbaceous, perennial, rhizomatous plants. There are a multitude of varieties and cultivars, as they are very popular in gardens all over the world. The generic name derives from two Greek words: hemera, "day" and kallos, "beauty", alluding to the short duration of its flowers, barely a day, although they are replaced by another on the same stem the following day. The flowers of Hemerocallis open in the morning and fade in the evening.
Its flowers generally range from a soft yellow to orange or red, although there are species and varieties with several colours in the flower, or with lilac or violet tones. Among the most common species are: H. citrina, H. esculenta, H. fulva, H. lilioasphodelus, H. middendorfii, H. minor or H. thunbergii.
The flowers and buds of some species are edible, and in some Asian countries they are cultivated for this purpose; in contrast to true lilies (genus Lilium), which are highly toxic.