The Daylily

These plants are perennial. The name Hemerocallis comes from the Greek words ἡ μέρα (hēmera) "day" and καλός (kalos) "beautiful". The flowers of most species open at sunrise and wither at sunset, possibly replaced by another one on the same stem the next day. Some species are night-blooming. Daylilies are not commonly used as cut flowers for formal flower arranging, yet they make good cut flowers otherwise as new flowers continue to open on cut stems over several days.

Originally native from Europe to China , Korea , and Japan , their large showy flowers have made them popular worldwide. There are over 60,000 registered cultivars. Only a few cultivars are scented. Some cultivars rebloom later in the season, particularly if their developing seedpods are removed.

Daylilies occur as a clump including leaves, the crown, and the roots. The long, often linear lanceolate leaves are grouped into opposite flat fans with leaves arching out to both sides. The crown of a daylily is the small white portion between the leaves and the roots, an essential part of the fan. Along the flower stem or scape, small leafy "proliferations" may form at nodes or in bracts. These proliferations form roots when planted and are the exact clones of the parent plant. Some daylilies show elongated widenings along the roots, made by the plant mostly for water storage and an indication of good health.

The flower consists of three petals and three sepals, collectively called tepals, each with a midrib in the same or in a contrasting color. The centermost section of the flower, called the throat, has usually a different and contrasting color. There are six (sometimes seven) stamens, each with a two-lobed anther. After pollination, the flower forms a seed pod on most varities.

Cultivars

Daylilies can be grown in USDA plant hardiness zones 1 through 11, making them some of the most adaptable landscape plants. Most of the cultivars have been developed within the last 100 years. The large-flowered clear yellow 'Hyperion', introduced in the 1920s, heralded a return to gardens of the once-dismissed daylily, and is still widely available. Daylily breeding has been a specialty in the United States , where their heat- and drought-resistance made them garden standbys during the later 20th century. New cultivars have sold for thousands of dollars, but sturdy and prolific introductions soon reach reasonable prices.

The Tawny Daylily (Hemerocallis fulva ), and sweet-scented H. lilioasphodelus (H. flava is an illegitimate name), colloquially called Lemon Lily, were early imports from England to 17th century American gardens and soon established themselves. Tawny Daylily is so widely growing wild that it is often considered a native wildflower. It is called Roadside or Railroad Daylily, and gained the nickname Wash-house or Outhouse Lily because it was frequently planted at such buildings.

Hemerocallis is one of the most hybridized of all garden plants, with registrations of new hybrids being made in the thousands each year in the search for new traits. Hybridizers have extended the plant's color range from the yellow, orange, and pale pink of the species, to vibrant reds, purples, lavenders, greenish tones, near-black, near-white, and more. However, a blue daylily is a milestone yet to be reached.

All daylilies are herbaceous perennials - some are evergreen or semi-evergreen while some go dormant in winter, losing their foliage.

A recent trend in hybridizing is to focus on tetraploid plants, with thicker petal substance and sturdier stems. Until this trend took root, nearly all daylilies were diploid. "Tets," as they are called by aficionados, have double the number of chromosomes as a diploid plant. Hemerocallis fulva 'Europa', H. fulva 'Kwanso', H. fulva 'Kwanso Variegata,' H. fulva 'Kwanso Kaempfer,' H. fulva var. maculata, H. fulva var. angustifolia ,and H. fulva 'Flore Pleno' are all triplods which cannot set seed and are reproduced solely by underground runners (stolons) and division. Usually referred to as a "double," meaning producing flowers with double the usual number of petals (e.g. , daylily 'Double Grapette'), 'Kwanzo' actually produces triple the usual number of petals.

Culinary use

The flowers of some species are edible and are used in Chinese cuisine. They are sold (fresh or dried) in Asian markets as gum jum or golden needles or yellow flower vegetables . They are used in hot and sour soup, daylily soup, Buddha's delight, and moo shu pork. The young green leaves and the tubers of some (but not all) species are also edible. The plant has also been used for medicinal purposes. Care must be used as some species can be toxic.