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White sweet-clover

(Melilotus albus)

Photo of white sweet clover
Photo credit: Paul Berry

Herbaceous biennial. First-year plants do not bloom. Second-year plants grow 3-5’ high and are bush-like. Erect stems are multi-branched and often hollow.

Overview

Other names for this plant include:
  • Common names: honey-clover, white melilot
  • Scientific names: Melilotus alba; M. albus var. annuus; M. leucanthus; M. officinalis subsp. albus
Ecological threat:
  • Invades prairies, savannas, dunes, roadsides and abandoned fields.
  • Fire stimulates germination of sweet clover seeds and can exacerbate invasions.

Classification in Wisconsin: Not regulated.

Identification

First-year plants: leaves are alternate, oblong, tri-lobed leaflets are finely-toothed. The terminal leaflet is on its own petiole.

Second-year leaves: Alternate, with 3 finely-toothed leaflets and clover-like but longer (1”) and thinner (1/3”) than other clovers. The middle leaflet grows on a short but distinct stalk.

Flowers: Five-parted, small, white, fragrant, pea-like flowers, clustered in dense racemes. Second-year plants bloom late spring through summer.

Fruits & seeds: One or two small seeds with hard seed coats produced per flower; up to 350,000 seeds per plant. Seeds remain viable in the soil for up to 30 years.

Roots: Strong taproot and extensive lateral roots.

Similar species: Yellow sweet clover (Melilotus officinalis) is usually shorter and has yellow flowers that bloom earlier.

Control

Mechanical: Hand pull small populations before seed set. Use brush-cutter for large populations. Late fall burn to stimulate germination followed by a late spring burn next season to eliminate second-year plants before seed set.

Chemical: Spray seedlings with 2,4-D (LR) in early spring.

Photos

View white sweet-clover pictures in our photo gallery!

Resources

Sources for content:
  • Czarapata, Elizabeth; Invasive Plants of the Upper Midwest: an illustrated guide to their identification and control. University of Wisconsin Press. 2005. Pg. 68-70
  • USDA Forest Service, Northeastern Area Forest Health Staff. Weed of the Week: Yellow Sweetclover [exit DNR].
Links for more information: