Herbs, annual, biennial, or short-lived perennial, unarmed. Stems usually erect or ascending, sometimes decumbent, glabrous or glabrescent. Leaves alternate, odd-pinnate; stipules present, adnate to petiole; petiolate; leaflets 3, blade margins usually dentate, rarely entire or subentire, surfaces glabrous or pubescent. Inflorescences pedunculate, (5–)8–80(–120)-flowered, axillary, racemes, usually elongating in fruit; bracts present or absent. Flowers papilionaceous, usually pendulous, sometimes upright; calyx campanulate, lobes 5, ± subequal; corolla yellow or white; stamens 10, diadelphous; anthers basifixed. Fruits legumes, stipitate, usually ± compressed, usually globose, subglobose, obovoid, or ovoid, sometimes lanceolate-rhomboid or elongated-elliptic, indehiscent or tardily dehiscent, reticulately or concentrically patterned with raised venation, thickly leathery, usually glabrous (pubescent in M. altissimus). Seeds 1 or 2 (or 3)[–5], usually ovoid, obovoid, oblong to subglobose, or ellipsoid, smooth or slightly tuberculate. x = 8.

Distribution

Introduced; Europe, Asia, n Africa, introduced also in temperate areas nearly worldwide.

Discussion

Species ca. 18 (6 in the flora).

Trigonella and Melilotus may merit amalgamation (P. Coulot and P. Rabaute 2013), and Melilotus has been subdivided in various ways (reviewed by G. A. Stevenson 1969). Most species of Melilotus have a characteristic vanillalike odor and a bitter taste, due to the presence of coumarins.

Some species of Melilotus are cultivated as forage crops, for soil improvement, erosion control, revegetation and reclamation plantings, and as honey plants. Some are significant weeds, including the cultivated species.

Some Melilotus specimens at GH and NY were collected from ballast sites and have been identified as M. neapolitanus Tenore ex Gussone or M. gracilis de Candolle; these are correctly identified as M. neapolitanus, according to the key written by G. A. Stevenson (1969). However, F. Sales and I. C. Hedge (1993) concluded that the name M. neapolitanus Tenore is confused, applied in the past to M. sulcatus Desfontaines and incorrectly applied by most authors to M. spicatus (Smith) Breistroffer. Regardless of the correct name, the species is not naturalized in the flora area.

Selected References

None.

Lower Taxa

Melilotus albus, Melilotus altissimus, Melilotus indicus, Melilotus officinalis, Melilotus sulcatus, Melilotus wolgicus

Key

1	Corollas white.	> 2
2	Flowers 3.5–5(–6) mm; pedicels 1–1.5(–2) mm; widespread, including Manitoba and Saskatchewan.	Melilotus albus
2	Flowers 3–3.5 mm; pedicels 2–4 mm; Manitoba, Saskatchewan.	Melilotus wolgicus
1	Corollas yellow.	> 3
3	Stipule margins dentate (mostly at base); legumes concentrically striated-veined.	Melilotus sulcatus
3	Stipule margins entire or subentire; legumes reticulate-veined, transversely rugose, or sigmoid-veined.	> 4
4	Flowers 1.5–3 mm.	Melilotus indicus
4	Flowers 4–7 mm.	> 5
5	Ovaries and young fruits appressed-pubescent.	Melilotus altissimus
5	Ovaries and young fruits glabrous.	Melilotus officinalis