Description from Flora of China
Trifolium officinale Linnaeus, Sp. Pl. 2: 765. 1753 [T. "M. officinalis"]; Brachylobus officinalis (Linnaeus) Dulac; Melilotus graveolens Bunge; M. officinalis f. suaveolens (Ledebour) H. Ohashi & Tateishi; M. suaveolens Ledebour.
Biennial herbs, sparsely puberulent to glabrescent. Stems erect, 40-100(-250) cm, longitudinally ridged. Stipules linear-falcate, 3-5(-7) mm, entire or with 1 tooth at base; petiole slender; leaflets obovate, broadly ovate, oblanceolate, to linear, 15-25(-30) × 5-15 mm, lateral veins running into teeth, 8-12 pairs, margins shallowly serrate. Racemes 6-15(-20) mm, 30-70-flowered, dense at first, becoming lax in anthesis; bracts equal to pedicels, 1.5-2 mm. Corolla yellow, 4.5-7 mm; standard ± equal to wings and keel. Ovary narrowly ovate; ovules (4-)6(-8). Legume ovoid, 3-5 × ca. 2 mm, veins transversely reticulate, dark brown, apex with persistent style. Seeds 1 or 2, yellowish brown, ovoid, ca. 2.5 mm, smooth. Fl. May-Sep, fr. Jun-Oct.
Sandy grasslands, hillsides, ravine shores, margins of mixed woodlands. Throughout China [Asia, Europe].