|Melilotus albus (L.) Medikus
by Emily Nelson, Native Plants Class
Common names: White sweetclover, White Melilot.
Synonymy: M. alba Medikus.
Etymology: The genus “meli” means honey, and the epithet “albus” means white and probably refers to the white color of the flowers.
Growth form: White sweetclover is a many-stemmed herbaceous plant, typically growing 3 to 8.5 feet tall (9).
Roots: Little root growth occurs until late summer of the plant’s first year. By the second year the white sweetclover will have a strong taproot (can grow 50+ inches long) (5, 8).
Stem: Often only one upright, branched stem grows early in the sweetclover’s life, though it may develop up to ten glabrous green stems by second year (8, 2, 7).
Leaves: Leaves are alternative, truncate and pinnate-trifoliate with narrow obovate to lanceolate-oblong leaflets whose margins are serrated around the tip of the leaf that extends more than half-way back on either side to the base (1, 2, 7).
Inflorescence/flowers: The inflorescence consists of about 40 to 80 white flowers with corollas usually 4 - 7 mm long and green calyx 1 - 2 mm long. The small flowers are arranged in terminal and axillary racemes, typically 2 to 8 inches long (1, 6).
Fruit: The fruit are small net-veined pods 3 – 5 mm long. Each pod contains 1 - 2 seeds with a hard seed coat, allowing them to maintain viability in the soil for over 20 years (1, 8).
Similar species: Melilotus officinalis (L.) Lam. (Yellow sweetclover) is very similar to white sweetclover with the exception of yellow to cream-colored flowers and cross-ribbed pods. Melilotus indica (L.) All. (Indian sweetclover) is less common than both white and yellow sweetclovers and has a mix of the yellow flowers with the net-veined pods, yet has a shorter growth form and smaller, more densely arranged flowers. All of the North American sweetclovers descended from varieties originating in Europe and Asia (1, 10).
Life history: White sweetclover is primarily a biennial herb, with annual forms also existing (8).
Native/introduced: Introduced from Europe and Asia (1).
Phenology: In Arizona, White sweetclover flowers from March through October (6). Fruits are disseminated in the fall and spread mainly by wind and water (10).
Distribution: Common in open, well lit, disturbed sites, such as roadsides, waste areas and along gravely streamsides. White sweetclover can be found in Arizona across most of the state from 100 to 7,500 feet elevation, as well as across the entire continental United States, Alaska, Hawaii, and all of the Canadian provinces and territories (6, 10).
Forage: White sweetclover is considered a palatable and nutritious forage for all types of livestock, but may be potentially toxic if not cured properly when used for hay and has occasionally been the cause of bloat in pasturing cattle (8). Many species of wildlife also forage on white sweetclover, including elk, pronghorn antelope, bighorn sheep, deer, quail, partridge, and rabbits (3).
Soil improvement: White Sweetclover is a good source of atmospheric nitrogen fixation for both soil improvement and nearby or succeeding plant use and is also used to prevent soil erosion (1, 8, 9)
Ethnobotanical: White sweetclover has a fragrant vanilla scent and may be hung upside down as an air freshener and is perhaps best known as a very popular nectar source for honey bees (4, 6).
1. Ball, D.A., Cudney, D., Dewey, S.A., et al. 2001. Yellow sweetclover. Weeds
of the West. 337.
2. Fernald, M.L. 1950. Gray’s Manual of Botany. 8th Ed. American Book Co.,
3. Graham, E.H. 1941. Legumes for erosion control and wildlife. Misc.
Publ. 412. Washington, DC: U.S. Department of Agriculture. 153 p.
4. Hogan, P. and K. Huisinga. 1999. Melilotus albus. An annotated catalog of
the native and naturalized flora of Arizona. 36 p.
5. Martin, J. N. 1934. The relative growth rates and interdependence of
tops and roots of the biennial white sweet clover, Melilotus alba Ders.
American Journal of Botany. 21:140-159.
6. Parker, K.F. 1972. White sweetclover. An Illustrated Guide to Arizona
Weeds (A Complete Online Edition of the Printed Book). The University of
7. Rydberg, P.A. 1971. Flora of the prairies and plains of central North
America. Dover Publications, New York. 2: 503 p.
8. Smith, W. K. and H.J. Gorz. 1965. Sweetclover improvement. Advances in
Agronomy. 17: 163-231.
9. Thornburg, A.A. 1982. Plant materials for use on surface-mined
lands. SCS-TP-157. Washington, DC: U.S. Department of Agriculture, Soil
Conservation Service. 88 p.
10. Turkington, R.A., P.B. Cavers, and E. Empel. 1978. The biology of
Canadian weeds. 29. Melilotus alba Desr. And M. officinalis (L.) Lam. Can.
J. Pl. Sci. 58:523-537