Melilotus officinalis (Yellow Sweet Clover)
|Also known as:|
|Life cycle:||annual, biennial|
|Habitat:||part shade, sun; open fields, along roads|
|Bloom season:||June - September|
|Plant height:||2 to 6 feet|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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Flowers are clustered in spike-like racemes up to 6 inches long on branching stems, arising from leaf axils, and at the top of the plant. Individual flowers are about ¼ inch long, with 5 parts in a typical shape for a member of the Pea family. Large plants can take on a bushy appearance with numerous clusters of yellow flowers. Small plants may have only a few sparsely arranged branches.
Leaves and stems:
Leaves are compound in groups of 3 on a stalk about 1 inch long. Leaflets are ½ to 1 inch long, ¼ to ½ inch across, with small teeth around the edges, a rounded tip and short slender stalk. The shape can be oval or elliptical, or tapering to a narrow base with the widest point in the tip half of the leaflet. The color may be somewhat blue-green or gray-green. Stems are ridged or grooved, mostly hairless and green or tinged red.
Yellow Sweet Clover was brought to North America as a forage crop and quickly escaped cultivation. It invades roadsides, fields, and generally anywhere soil is disturbed and can invade high grade prairie. It likes fire and can erupt in an explosion of growth following a burn. White Sweet Clover (Melilotus alba) was once classified as a separate species (Melilotus albus), then lumped in with Yellow Sweet Clover, and is back to a separate species again. Yellow Sweet Cover starts blooming a couple weeks earlier than White and is a slightly smaller plant, but except for the flower color and some other more subtle differences is otherwise nearly identical.
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Photos by K. Chayka taken in Ramsey County. Photos courtesy Peter M. Dziuk taken in Anoka County.
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