Texas Invasives

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Federal Noxious Weed

TDA Noxious Weed

TPWD Prohibited Exotic Species

Invasive Plant Atlas of the US

NOTE:

means species is on that list.

Melilotus officinalis

Yellow sweet clover

Synonym(s): Melilotus alba, M. arvensis, M. leucanthus,
Melilotus lutea
Family: Fabaceae (Pea Family)
Duration and Habit: Annual, Biennial, Perennial Herb

Photographer: Dave Powell
Source: USDA Forest Service, Bugwood.org

Description

Plants can grow to approximately 6 1/2 ft. (2 m) in height and can sometimes be woody at the base. Leaves are ovate to oblong, entire, stipulate and 0.4-1 in. long. Flowering occurs from April to September, when yellow, pea-like flowers develop in a branched inflorescence at the tips of the flowering stems. Flowers are less than 1/4 in. long. Fruits are small, circular, wrinkled and light brown pods that contain one seed.

Native Lookalikes: Currently no information available here yet, or there are no native Texas species that could be confused with Yellow sweet clover.

Ecological Threat: Threatens recovering prairies because it easily invades open areas through allelopathic chemicals forming dense monocultures which competes against native vegetation for resources and in turn inhibits native plant growth. Yellow sweetclover also reduces the occurrence of natural fires and degrade native grassland communities that depend on frequent fires. It is similarly an unwanted invader of rocky, open, calcareous glades and woodlands. It can degrade natural communities by growing tall and shading native sun-loving species.

Biology & Spread: It is a prolific seeder (35,000-100,000 seeds/plant), with seeds that remain viable for many years, and well adapted to a wide range of habitats. Therefore, even when its use in agriculture has declined in recent years, the likelihood of it colonizing new areas still remains high.

History: Yellow sweet clover was introduced into North America as a forage crop in the 1900s. In Alaska and Canada, this species is a serious problem on waterways because it is invading glacial river floodplains. Currently, it is recognized as a conservation problem in North America because it is invading critical natural areas such as national parks and protected lands.

U.S. Habitat: Plants occur along roadsides, in open fields, pastures and other disturbed areas.

Distribution

U.S. Nativity: Introduced to U.S.

Native Origin: Eurasia.

U.S. Present: AK, AL, AR, AZ, CA, CO, CT, DE, FL, GA, HI, IA, ID, IL, IN, KS, KY, LA, MA, MD, ME, MI, MN, MO, MS, MT, NC, ND, NE, NH, NJ, NM, NV, NY, OH, OK, OR, PA, PR, RI, SC, SD, TN, TX, UT, VA, VT, WA, WI, WV, WY

Distribution in Texas: Widespread throughout the state.

Mapping

Invaders of Texas Map: Melilotus officinalis
EDDMapS: Melilotus officinalis
USDA Plants Texas County Map: Melilotus officinalis

Invaders of Texas Observations

List All Observations of Melilotus officinalis reported by Citizen Scientists

OBS# 3047

OBS# 7634

OBS# 7159

Native Alternatives

Management

Manual- Manual methods include hand pulling before seeds are set, cutting to ground level when plants are in full bloom, mowing close to the ground when seedlings are 6-8 inches tall. For very dense small patches, cutting with a power brush-cutter using a heavy duty saw blade is effective. The stand should be cut just before flowering, and checked a week later for missed or partly cut plants.

Prescribed Burns- Sweetclover response to carefully timed seasonal burns using good management practices. A burn schedule such as a dormant season burn (late fall or early spring) to stimulate germination in the subsequent growing season, followed by a later spring burn the next season to eliminate the second year plants before they set seed has been effective.

Chemical- Spray with 2, 4-D in early spring when seedlings are very small.

USE PESTICIDES WISELY: ALWAYS READ THE ENTIRE PESTICIDE LABEL CAREFULLY, FOLLOW ALL MIXING AND APPLICATION INSTRUCTIONS AND WEAR ALL RECOMMENDED PERSONAL PROTECTIVE GEAR AND CLOTHING. CONTACT YOUR STATE DEPARTMENT OF AGRICULTURE FOR ANY ADDITIONAL PESTICIDE USE REQUIREMENTS, RESTRICTIONS OR RECOMMENDATIONS. MENTION OF PESTICIDE PRODUCTS ON THIS WEB SITE DOES NOT CONSTITUTE ENDORSEMENT OF ANY MATERIAL.

Text References

U.S. Forest Service. Weed of the Week: Yellow Sweetclover. Accessed February 2009: http://www.na.fs.fed.us/fhp/invasive_plants/weeds/yellow_sweetclover.pdf.

Klein H, 2011. Yellow sweetclover Melilotus officinalis (L.) Lam. Anchorage, Alaska, USA: Alaska Natural Heritage Program, University of Alaska, 2 pp. http://accs.uaa.alaska.edu/files/invasive-species/Melilotus_officinalis_BIO_MEOF.pdf

Wolf, J. J., Beatty, S. W., Seastedt, T. R., 2004. Soil characteristics of Rocky Mountain National Park grasslands invaded by Melilotus officinalis and M. alba. Journal of Biogeography, 31(3) 415-424.

Online Resources

https://www.cabidigitallibrary.org/doi/10.1079/cabicompendium.33697

Bugwood Network. Bugwood.com

USDA-NRCS, 2017. The PLANTS Database. Baton Rouge, USA: National Plant Data Center. http://plants.usda.gov/