Melilotus officinalis
yellow sweetclover
Overview
Melilotus officinalis is a tall biennial legume in the pea family, reaching 2-6 feet (60-180 cm) on slender, branching stems. The leaves are divided into three narrow leaflets 0.5-1 inch (1-2.5 cm) long with finely toothed edges. From late spring through autumn, small yellow pea-like flowers, each about 0.2 inch (5-6 mm) long, are carried in long, tapering racemes that rise above the foliage. The whole plant carries the sweet scent of coumarin, strongest as the cut foliage dries, recalling fresh hay or vanilla. It grows from a deep taproot, fixing nitrogen and tolerating poor, dry, and alkaline soils, which has made it widely sown for forage, green manure, and honey production. Native to Europe and Asia, it has naturalized across North America, where it spreads readily along roadsides and into prairies and is treated as an invasive weed of grasslands. When the cut plant molds, coumarin converts to dicoumarol, an anticoagulant that causes fatal internal bleeding in livestock fed spoiled hay and the basis for the discovery of warfarin.
Native Range
Native to Europe and temperate Asia, in grasslands, roadsides, and disturbed open ground. It has naturalized throughout North America and is widespread in prairies, fields, and waste places.Suggested Uses
Sown as a forage legume, green manure, and cover crop on poor soils, and grown by beekeepers as a nectar plant. In restoration it is generally avoided because of its invasive spread in grasslands. The dried foliage has been used to scent and flavor some cheeses and tobacco.How to Identify
Appearance
Size & Dimensions
Height2' - 6'
Width/Spread1' - 2'
Reaches mature size in approximately 2 years
Bloom Information
Blooms over a long season from late spring into autumn, generally May through September, peaking in mid-summer. The many small yellow flowers are a heavy nectar source and a noted honey plant. Each raceme opens from the base upward over several weeks.
Detailed Descriptions
Foliage Description
GreenGrowing Conditions
Sun Requirements
Requires 6-12 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight