Oenothera biennis L., Sp. Pl. 346. 1753.
月見草
Biennial herb with basal overwintering rosette; stems erect, 30-200 cm tall; pubescence glandular, long-spreading (often with red blister-like bases), and strigillose. Cauline leaves oblanceolate to elliptic, 5-22 cm, subentire to dentate, flat, often lobed toward base. Flowers numerous in dense spikes; floral tube (20-)25-40 mm, straight in young buds; sepals 12-20(-28) mm, green, rarely reddish, with free tips in bud 1.5-3 mm; petals 10-25(-30) mm, yellow fading duller or orange; anthers 3-6(-9) mm long; pollen 50% fertile; stigma surrounded by anthers. Capsule narrowly lanceolate, usually straight, 20-40 mm long, 4-6 mm wide. Seeds in 2 rows per locule, 1-2 mm, angled, reticulate and irregularly pitted. 2n = 14. Flowers (Jun) Jul-Oct; fruit Jun-Nov.
PINGTUNG: Manzhou, Koidzumi s.n. 1936.
Native to central and eastern North America, now widely naturalized in Asia, Europe, Australia, South America, and Africa; only one specimen known from Taiwan. Mostly in open disturbed places, such as old or irrigated fields and roadsides.