Melilotus officinalis Seeds | Yellow Melilot
LATIN NAME: Melilotus officinalis
COMMON NAME: Yellow Melilot, Yellow Sweet Clover, Common Melilot
Plant Profile
Yellow melilot is a biennial clover relative, one to one and a half metres tall, with trifoliate leaves and long spikes of small yellow pea flowers from June to September. It grows on roadsides, waste ground and dry meadows across Europe and western Asia, and it has been spread widely as a forage plant.
Crushed leaves smell of new-mown hay, a scent that comes from coumarin. That single compound has shaped the plant’s history, from perfume to a cattle disease that led, indirectly, to the discovery of warfarin. The taproot is deep and tough, which makes the plant hard to pull once established, and it fixes nitrogen at the roots.
Science & Biotechnology
Coumarin itself is not an anticoagulant. When sweet clover hay is poorly dried or spoils in the silo, moulds convert it to dicoumarol, a bis-hydroxycoumarin that blocks vitamin K recycling and causes internal bleeding. The disease, sweet clover disease, killed cattle across the American Midwest in the 1920s.
Work on that disease produced dicoumarol and then warfarin, first as a rodenticide and later as a medicine. The irony is that the same plant is now used as a green manure and bee forage, and its coumarin content is a quality issue in hay rather than a hazard in the field.
Uses & Benefits
Melilot appears in European herbal practice as a poultice for bruises and as a mild venous tonic, and it is an ingredient in some anti-inflammatory ointments. The flowers are a good nectar source and give a pale, strongly flavoured honey.
Internally it is used cautiously, at low dose and not for long periods, because of the coumarin content and the possibility of interaction with anticoagulants. It should not be used by anyone on warfarin, and spoiled hay from melilot should never be fed to livestock. In the field the plant is valued as bee forage and as a green manure, turned in before the stems harden. Hay cut late and dried badly is the dangerous material, and a smell of new-mown hay in a bale is a warning rather than a recommendation.
Growing from Seed
Seed has a high proportion of hard coats and benefits from scarification or a hot-water soak. Sow in spring or late summer, either broadcast or in rows, at two grams per square metre.
The plant fixes nitrogen, tolerates drought and poor soil, and will self-sow freely once established. It is biennial, flowering in the second year, so a patch needs to be allowed to set seed if it is to persist. In some regions it is classed as invasive, and it should not be sown near remnant grassland. Mowing after flowering prevents a seed set that can carpet a whole verge within two years.
Our Take
A plant whose scent tells you exactly what it contains, and whose history is a warning about how much a curing process can change a crop.
Related Reading
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