2. Hemerocallis lilioasphodelus Linnaeus, Sp. Pl. 1: 324. 1753.
Yellow daylily, lemon daylily
Hemerocallis flava (Linnaeus) Linnaeus
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).