White Sweetclover

Melilotus albus is an annual or biennial legume that can reach 2.5 m (8 ft 2 in) in height. The light green stems are round or slightly terete (furrowed on all sides), glabrous (smooth), and often branched. The 1/2 - 2 inch long alternate leaves are trifoliate and sparsely distributed along the stem and alternate in arrangement. The upper stems terminate in narrow racemes of white flowers about 2-6 inches long that have a tendency to hang downward from the central stalk of the raceme. Each flower is about 1⁄3 inch (8.5 mm) long, consisting of 5 white petals and a light green calyx with 5 teeth. Flowers are small, floppy, tubular at the base and become broader toward the outer edges and wing and keel petals are about equal in length. The ovoid seedpods are black to dark grey, smooth or slightly reticulated and about 0.3 inches long (3-4mm). Each pod usually contains one, but sometimes two, yellow seeds that are ovate to kidney-shaped. Plants generally flower and die during the second year of growth. The blossoming period occurs from early summer to fall, reaching its peak during mid-summer, and lasts for about 1–2 months for a colony of plants. An extensive root system of deep taproots imparts resistance to summer drought. The roots of M. albus are associated with nitrogen-fixing bacteria.

Similarity to other species. …

White sweetclover is native to much of Asia and southern Europe, from France and Spain to Kazakhstan and Myanmar, and also northeastern Africa. M. albus has been introduced from Eurasia into South Africa, North and South America, New Zealand, Australia, and Tasmania, as well as many parts of Europe outside its native range. In the US, the species is considered most common in the upper Midwest and Great Plains regions, including Kentucky, Nebraska, Tennessee and Wisconsin. White sweetclover was brought to North America as early as 1664 as a forage crop. Since then, it has spread from cultivation and thrives in waste places and roadsides. White sweetclover is found in every state in the United States and all but 2 Canadian provinces. It establishes in aspen woodlands and prairies in Canada and the lower 48 states and riparian communities in Alaska. The early spread of M. albus was probably facilitated by beekeepers and agriculturalists, as it can be an important fodder crop and food source for honey bees, and it was brought to Alaska in 1913 as a potential forage and nitrogen (N) fixing crop.

White sweetclover has high seed germination rates. Most germination and development occurs in spring - temperatures of less than 59 degrees F are optimal for germination.

White and yellow sweetclover are considered valuable honey plants, and the foliage and seeds are consumed by wildlife. They are frequently cultivated for livestock forage and as a cover crop. Melilotus albus has been promoted in Australia for use on dryland soils affected by salinity. It has been used in herbal medicine. It includes dicoumarol, which is an anticoagulant. It also has a high sugar content.