E-Flora BC: Electronic Atlas of the Flora of British Columbia

Melilotus officinalis (L.) Lam.
yellow sweet-clover (yellow sweetclover)
Fabaceae (Pea family)

Introduction to Vascular Plants

© Brian Klinkenberg  Email the photographer   (Photo ID #29885)

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Distribution of Melilotus officinalis
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Species Information

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Biennial or annual herb from a strong taproot, sweet-scented in drying; stems erect, 0.5-2 m tall, freely branched, glabrous to sparsely short-hairy.
Alternate, pinnately compound; leaflets 3, elliptic-oblong to egg-shaped, short-hairy to glabrous, 1-4 cm long, the margins fine-toothed to near the base; stipules entire or with 1-3 basal teeth, 5-10 mm long, joined at the base to the leaf stalk.
Inflorescence a slender, spike-like, axillary raceme of 20 to 50 or more pea-like flowers, the racemes 3-15 cm long, on stalks from shorter to longer than the leaves; corollas yellow, 5-7 mm long, the banner and wings equal to or longer than the keel; calyces bell-shaped, the tube 1-2 mm long, the teeth narrowly lance- to awl-shaped, as long as the tube.
Pods, egg-shaped, somewhat flattened but still plump, nodding, 3-5 mm long, somewhat leathery, glabrous, cross-ribbed, 1-chambered; seeds 1 or 2.

Source: The Illustrated Flora of British Columbia

USDA Species Characteristics

Flower Colour:
Blooming Period:
Fruit/Seed characteristics:
Colour: Yellow
Present from Summer to Fall
According to the USDA, this species is a known allelopath.
Source:  The USDA

Habitat / Range

Mesic to dry fields, roadsides and waste places; frequent in S half of BC east of the Coast-Cascade Mountains, rare to the W and N; introduced from Eurasia.

Source: The Illustrated Flora of British Columbia


Ecological Framework for Melilotus officinalis

The table below shows the species-specific information calculated from
original data (BEC database) provided by the BC Ministry of Forests and Range.
(Updated August, 2013)

Site Information
Value / Class




Elevation (metres) 385 895 1813
Slope Gradient (%) 0 24 80
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
50 192 335
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
0 3 7
Modal Nutrient Regime
Number of field plots
 species was recorded in:
Modal BEC Zone Class
All BEC Zones (# of stations/zone) species was recorded in: BG(6), BWBS(2), ESSF(2), ICH(4), IDF(31), MS(4), PP(5), SBPS(1), SBS(2)


The climate type for this species, as reported in the: "British Columbia plant species codes and selected attributes. Version 6 Database" (Meidinger et al. 2008), is not evaluated, unknown or variable.

Synonyms and Alternate Names

Melilotus arvensis Wallr.
Melilotus leucanthus W. D. J. Koch ex DC.
Melilotus lutea Gueldenst.
Melilotus officinalis var. micranthus O. E. Schulz

Taxonomic and Nomenclatural Links

Additional Photo Sources

General References