A daylily, day lily or ditch-lily is a flowering plant in the genus Hemerocallis /ˌhɛmɪroʊˈkælɪs/,[2] a member of the family Asphodelaceae, subfamily Hemerocallidoideae, native to Asia.

[6] Typically Hemerocallis flowers have three similar petals and three sepals, collectively called tepals, and each have a midrib.

[4][7] The flowers of most species open in early morning and wither during the following night, possibly replaced by another one on the same scape the next day.

[4] Despite their common name, daylilies are not true lilies (plants from the genus Lilium, family Liliaceae).

These include:[9] The name Hemerocallis comes from the Greek words ἡμέρα (hēmera) "day" and καλός (kalos) "beautiful".

[citation needed] Daylilies have been found growing wild for millennia throughout China, Mongolia, northern India, Korea, and Japan.

[10] There are thousand-year-old Chinese paintings showing orange daylilies that are remarkably similar to the flowers that grace modern gardens.

Daylilies were first brought to North America by early European immigrants, who packed the roots along with other treasured possessions for the journey to the New World.

By the early 1800s, the plant had become naturalized, and a bright orange clump of flowers was a common sight in many homestead gardens.

The orange or tawny daylily (Hemerocallis fulva), common along roadsides in much of North America, is native to Asia.

As popular as daylilies were for many hundreds of years, it was not until the late 19th century that botanists and gardeners began to experiment with hybridizing the plants.

[12] The daylily has been nicknamed "the perfect perennial" by gardeners, due to its brilliant colors, ability to tolerate drought and frost and to thrive in many different climate zones, and for being generally low maintenance.

It is a vigorous perennial that lasts for many years in a garden, with very little care and adapts to many different soil and light conditions.

The large-flowered, bright yellow Hemerocallis 'Hyperion', introduced in the 1920s, heralded a return to gardens of the once-dismissed daylily, and is still widely available in the nursery trade.

Hybridizers have extended the genus' color range from the yellow, orange, and pale pink of the species, through vibrant reds, purples, lavenders, greenish tones, near-black, near-white, and more.

Hybridizers also seek to make cultivars cold-hardier by crossing evergreen and semi-evergreen plants with dormant varieties.

angustifolia, and H. fulva 'Flore Pleno' are all triploids that almost never produce seeds and reproduce almost solely by underground runners (stolons) and dividing groups by gardeners.

This annual award—as voted by American Hemerocallis Society (AHS) Garden judges—can be given only to a cultivar that has first received the Award of Merit not less than two years previously.

[16] In the UK the following cultivars have gained the Royal Horticultural Society's Award of Garden Merit:[17] Contarinia quinquenotata, commonly known as the daylily gall midge, is a small gray insect infesting the flower buds of Hemerocallis species causing the flower to remain closed and rot.