Melilotus albus
Melilotus
honey-clover, white melilot, white sweet-clover
melilot, sweet-clover
erect or ascending.
usually erect or ascending, sometimes decumbent, glabrous or glabrescent.
stipules lanceolate-subulate to setaceous, 4–6(–10) mm, margins usually entire, sometimes toothed at base;
leaflet blades narrowly oblong-obovate to suborbiculate-oblong, 10–24(–50) × 5–12(–15) mm, margins dentate.
alternate, odd-pinnate;
stipules present, adnate to petiole;
petiolate;
leaflets 3, blade margins usually dentate, rarely entire or subentire, surfaces glabrous or pubescent.
40–80(–120)-flowered.
pedunculate, (5–)8–80(–120)-flowered, axillary, racemes, usually elongating in fruit;
bracts present or absent.
1–1.5(–2) mm.
3.5–5(–6) mm;
corolla white;
ovary glabrous.
papilionaceous, usually pendulous, sometimes upright;
calyx campanulate, lobes 5, ± subequal;
corolla yellow or white;
stamens 10, diadelphous;
anthers basifixed.
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).
obovoid, subglobose, or globose-ovoid, 3–5 mm, reticulate-veined, glabrous.
1 or 2(or 3), ovoid, (1.7–)2–2.5(–3.5) mm.
1 or 2 (or 3)[–5], usually ovoid, obovoid, oblong to subglobose, or ellipsoid, smooth or slightly tuberculate.
= 8.
= 16.
Melilotus albus
Melilotus
Melilotus albus is extremely variable in Eurasia, and has been divided into many infraspecific taxa. It is the most important economic species in Melilotus, often grown as a crop, green manure, and honey plant, and posing a widespread weed problem.
Essentially all white-petaled Melilotus plants growing outside of cultivation in North America are M. albus; herbarium specimens often do not show the color well, sometimes resulting in misidentification, particularly between M. albus and M. officinalis. Aside from petal color, the species are quite similar. The venation areolae on the mature pods tend to differ: the raised venation ridges tend to form an irregular reticulation on the mature fruits of M. albus; they tend to form transverse areolae on the fruits of M. officinalis (S. J. Darbyshire and E. Small 2018). Although M. albus and M. officinalis are sometimes merged, there are very strong barriers to interbreeding between the two (G. T. Webster 1955; M. Maekawa et al. 1991), in addition to geographical and ecological differences, which justify their continued recognition as separate species.
P. Coulot and P. Rabaute (2013) included Melilotus albus in Trigonella sulcata (Desfontaines) Coulot & Rabaute (treated here as M. sulcatus). Most botanical literature incorrectly lists the authority for Melilotus albus as Desrousseaux in Lamarck instead of Medikus.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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.)
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 |
- Local floras:
BC, 
CA, 
OR, 
WA - Local Web sites: CalFlora, CalPhotos,
Flora NW, 
Go Botany, 
IL Wildflowers, 
KS Wildflowers, 
LA Plants, 
MD Biodiversity, 
MI Flora, 
MN Wildflowers, 
MO Plants, 
PNW Herbaria 
WildflowerSearch
iNaturalist (observations)
USDA Plants Database- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
