Plants 5-10 dm; roots enlarged, fibrous. Leaf blade dark green, 5-6.5 dm × 0.8-1.5 cm. Scape closely branched distally, 8-12-flowered, taller than foliage. Flowers often remaining open into night, fragrance strongly sweet, lemony; perianth tube shortly funnelform, 1.5-2.5 cm; tepals uniformly pale to bright lemon yellow, veins parallel; outer tepals 5-7 × 1-1.3 cm, margins smooth; inner tepals 5-7.5 × 1-2 cm, margins smooth; filaments 3-3.5 cm; anthers 2-3 mm; ovary 5-6 mm; style white to yellow, 7-8 cm; pedicel 2-4 mm. Capsules fully developed, oblong-elliptic, (2-)3-4 × (1-)1.5-2 cm. Seeds black, round or angular by compression, 3-5 mm, shiny. 2n = 22. Flowering summer. Roadsides, waste places, open woods; 0--500 m; introduced; N.B., Ont., Que.; Ark., Conn., Ill., Ind., Ky., Maine, Md., Mass., Mich., Minn., Miss., N.J., N.Y., N.C., Ohio, Okla., Pa., R.I., Texas, Vt., Va., W.Va., Wis.; e Asia; naturalized Europe. Hemerocallis lilioasphodelus was an early introduction to Europe, where it naturalized, and then to North America (W. J. Dress 1955; Hu S. Y. 1968; W. B. Zomlefer 1998). This diploid species escapes only sporadically, unlike the more aggressive H. fulva, with true naturalization frequently questioned (W. B. Zomlefer 1998).
Perennial herb 0.5 - 1 m tall Leaves: numerous, basal, dark green, long and narrow, to 1 m long and 2 cm wide. Flowers: lemon yellow, to 2 cm long and 7.5 cm wide, shortly funnel-shaped, with six tepals that spread and curve backwards. Stamens six. Flowers lemon-scented and lasting a single day. Fruit: a capsule, 2 - 4 cm long, 1 - 2 cm wide, oblong to elliptic. Flowering stalk: (scape) leafless, branched, taller than foliage, and with eight to twelve large flowers.
Similar species: Hemerocallis fulva is similar but has orange flowers. It is also very rare in the wild, whereas H. lilioasphodelus is common.
Flowering: late May to early June
Habitat and ecology: Introduced from Asia. A rare escape from cultivation that has been found growing along a road.
Occurence in the Chicago region: non-native
Etymology: Hemerocallis comes from the Greek words hemera, meaning day, and kallos, meaning beauty. Thus, Hemerocallis means "beautiful for a day." Lilioasphodelus is a combination of the words lily and asphodelus, a lily-like plant of which the roots were eaten.