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melilot, sweet-clover

furrowed melilot, grooved melilot, Mediterranean sweetclover

Habit Herbs, annual, biennial, or short-lived perennial, unarmed. Herbs annual, 10–70 cm.
Stems

usually erect or ascending, sometimes decumbent, glabrous or glabrescent.

erect or ascending.

Leaves

alternate, odd-pinnate;

stipules present, adnate to petiole;

petiolate;

leaflets 3, blade margins usually dentate, rarely entire or subentire, surfaces glabrous or pubescent.

stipules ovate-acuminate or subulate, 5–10 mm, margins dentate (mostly at base);

leaflet blades obovate, oblanceolate, or oblong-cuneate, 10–25 × 5–12 mm, margins dentate.

Racemes

(5–)8–20(–50)-flowered.

Inflorescences

pedunculate, (5–)8–80(–120)-flowered, axillary, racemes, usually elongating in fruit;

bracts present or absent.

Pedicels

1–2 mm.

Flowers

papilionaceous, usually pendulous, sometimes upright;

calyx campanulate, lobes 5, ± subequal;

corolla yellow or white;

stamens 10, diadelphous;

anthers basifixed.

(2.5–)3–4(–8) mm;

corolla yellow;

ovary glabrous.

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).

Legumes

globose or ovoid, (2–)3–4(–5.5) mm, concentrically striate-veined, glabrous.

Seeds

1 or 2 (or 3)[–5], usually ovoid, obovoid, oblong to subglobose, or ellipsoid, smooth or slightly tuberculate.

1(or 2), oblong-subglobose or ovoid, (2–)2.5–3(–3.5) mm.

x

= 8.

2n

= 16 [Eurasia].

Melilotus

Melilotus sulcatus

Phenology Flowering spring–summer.
Habitat Ruderal areas.
Elevation 0–200 m. (0–700 ft.)
Distribution
from USDA
Europe; Asia; n Africa [Introduced in North America; introduced also in temperate areas nearly worldwide]
[BONAP county map]
from FNA
AL; NJ; PA; Europe; Asia; Africa [Introduced in North America]
[BONAP county map]
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.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

In Europe, Melilotus sulcatus appears to intergrade or at least hybridize with M. infestus Gussone [M. sulcatus subsp. infestus (Gussone) Bonnier & Layens] and M. segetalis (Brotero) Seringe [M. sulcatus subsp. segetalis (Brotero) P. Fournier].

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Corollas white.
→ 2
2. Flowers 3.5–5(–6) mm; pedicels 1–1.5(–2) mm; widespread, including Manitoba and Saskatchewan.
M. albus
2. Flowers 3–3.5 mm; pedicels 2–4 mm; Manitoba, Saskatchewan.
M. wolgicus
1. Corollas yellow.
→ 3
3. Stipule margins dentate (mostly at base); legumes concentrically striated-veined.
M. sulcatus
3. Stipule margins entire or subentire; legumes reticulate-veined, transversely rugose, or sigmoid-veined.
→ 4
4. Flowers 1.5–3 mm.
M. indicus
4. Flowers 4–7 mm.
→ 5
5. Ovaries and young fruits appressed-pubescent.
M. altissimus
5. Ovaries and young fruits glabrous.
M. officinalis
Source FNA vol. 11. Author: Ernest Small. FNA vol. 11.
Parent taxa Fabaceae > subfam. Faboideae Fabaceae > subfam. Faboideae > Melilotus
Sibling taxa
M. albus, M. altissimus, M. indicus, M. officinalis, M. wolgicus
Subordinate taxa
M. albus, M. altissimus, M. indicus, M. officinalis, M. sulcatus, M. wolgicus
Synonyms Trifolium Trigonella sulcata
Name authority (Linnaeus) Miller: Gard. Dict. Abr. ed. 4, vol. 2. (1754) Desfontaines: Fl. Atlant. 2: 193. (1799) — (as sulcata)
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