Hemerocallis fulva, the Orange Daylily, Tawny Daylily, Tiger Daylily, Fulvous Daylily or Ditch Lily (also Railroad Daylily, Roadside Daylily, Outhouse Lily, Tiger Lily, and Wash-house Lily), is a species of daylily native to Asia. It is very widely grown as an ornamental plant in temperate climates for its showy flowers and ease of cultivation. It is not related to true lilies, but gets its name from the similarity of the flowers and from the fact that each flower lasts only one day.
It is an herbaceous perennial plant growing from tuberous roots, with stems 40–150 cm tall. The leaves are linear, 50–90 cm long and 1–2.8 cm broad. The flowers are 5–12 cm across, orange-red, with a pale central line; they are produced from early summer to late autumn on spikes of 10–20, with the individual flowers opening successively, each one only lasting one day. The fruit is a three-valved capsule 2–2.5 cm long and 1.2–1.5 cm broad which splits open at maturity to release the seeds.
Both diploid and triploid forms are known in the wild, but most cultivated plants are sterile triploids which only reproduce vegetatively by stolons or division. At least four botanical varieties are recognized, including the typical triploid var. fulva, the diploid, long-flowered var. angustifolia (syn.: var. longituba), the triploid var. kwanzo, where the stamens are modified into additional petals, and the evergreen var. aurantiaca.
Orange daylily is native to Asia from the Caucasus east through the Himalaya to China, Japan, and Korea. Orange daylily persists where planted, making them a very good garden plant.
Hemerocallis fulva var. fulva has escaped from cultivation across much of the United States and parts of Canada and has become a weedy or invasive species. It persists also where dumped and spreads more or less rapidly by vegetative increase into woods and fields and along roadsides and ditches, hence the common name Ditch Lily. It forms dense stands that exclude native vegetation, and is often so common that it is mistaken for a native species.
The tubers, inflorescences, buds and flowers can all be cooked and eaten. Dried or fresh flowers are used in Chinese, Japanese, Korean, Thai, and Vietnamese cooking, and are known as golden needles.