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Japanese Clover

Kummerowia striata

Summary 7

Kummerowia striata is a species of flowering plant in the legume family known by the common name Japanese clover. It is native to much of Asia and it is present in the eastern United States as an introduced species.

Control 8

Please contact your local agricultural extension specialist or county weed specialist to learn what works best in your area and how to use it safely. Always read label and safety instructions for each control method. Trade names and control measures appear in this document only to provide specific information. USDA, NRCS does not guarantee or warranty the products and control methods named, and other products may be equally effective.

Habitat characteristics 9

More info for the terms: cover, frequency

The clovers are most common in old fields, pastures, open woodlands, and along roads and stream banks [38,44,49,52,65,139]. Disturbed sites are often habitat for the clovers in recreation areas, wildlife refuges, and state parks. Disturbed sites typically include visitor-use areas, mowed lawns, rights-of-way, fire breaks, boat ramps, and/or parking areas [59,61,62,69].

Japanese and Korean clovers tolerate a wide range of environmental conditions. During a phytosociological study of weedy old fields in Scotland County in North Carolina's Upper Coastal Plain, Japanese clover "did not exhibit an exact affinity to specific edaphic conditions" [128]. Both clovers have been reported in cedar glade communities in the southeastern United States. Cedar glades occur in open areas on calcareous soils and are characterized by high sunlight levels, high summer soil temperatures, and extreme soil moisture levels that range from saturated or flooded to below the permanent wilting point [13].

Climate: The US distribution of Japanese and Korean clovers is limited by climatic tolerances. The northern boundary represents the area at which plants fail to reproduce before the first killing frost, and the western boundary represents areas that receive too little moisture to support the clovers (review by [93]).

Soils: While growth of Japanese and Korean clovers may be best on fertile, well-drained soils [49,93,140], plants survive in a variety of soil textures and in infertile, acidic, or limestone soil types. Both clovers have been reported on dry soils in West Virginia [139], sands in eastern Texas [38] and Missouri [142], sandy loams on the Coastal Plain, and clays in the Piedmont [58]. In the southeastern United States, the clovers grew best on fertile bottomlands, and although described as fairly drought tolerant, plants were most productive in areas with "adequate" moisture [58]. In 2- to 3-year-old fields in South Carolina, production of Japanese clover was greatest (13.5 g/m²) in fields with poorly drained soils (44% silt+clay in subsoil). Productivity was much lower (0.5-2.7 g/m²) on soils with moderate to excellent drainage (9-20% silt+clay in subsoil) [112]. While soil may have been important to Japanese clover abundance, past land use and proximity to a clover seed source were also likely important. Growth of the clovers can also be good on eroded, acidic soils with low levels of phosphorus (review by [93]). A review reports that Korean clover is less tolerant of acidic soils and more tolerant of alkaline soils than Japanese clover (review by [113]).

Two studies monitored the growth of Korean clover in old-field soils with differing textures and moisture and pH levels. Productivity varied on the different soil types studied but not consistently with soil moisture, fertility, or pH. In the greenhouse, germination of Korean clover was nearly 100% on both eroded and intact field soils collected near Ashland, Missouri. At the end of the growing season, however, the average biomass of Korean clover was greater on eroded (108.2 g/m²) than intact (89.2 g/m²) soils. Eroded soils lacked an A horizon and had a clay content that was nearly twice that of intact soils. Eroded soils had lower average growing-season moisture content (10.6%) than intact soils (12.2%). Based on these findings and results from a weeding experiment, researchers concluded that Korean clover was most "competitive" on poor, eroded soils [56]. In southeastern Iowa, Korean clover growth was compared on 3 eroded old-field sites: 2 upland and 1 lowland site (see table below for soil descriptions of these sites). Korean clover established and grew well on all sites, but establishment and growth were best on lowland sites. Available soil moisture during July, the driest growing-season month, was greatest for upland Weller soils. Soil moisture was evaluated in the top 6 inches (15 cm) of soil, where Korean clover roots were confined [16]. Soil characteristics of upland and lowland sites in southeastern Iowa that supported Korean clover [16] Soil type (site) Surface texture Average topsoil depth (inches) Acidity Fertility Bottomland (lowland) fine sandy loam 6-8 moderately acidic fair-medium Lindley (upland) loam 2-4 moderately acidic medium-low Weller (upland) silt loam 4-6 highly acidic medium-low

Flooding: The following studies indicate that both clovers tolerate some flooding but that Japanese clover may be more tolerant than Korean clover. Large Japanese clover populations are common along floodplains in Japan. Along the Ohta River floodplain in Hiroshima Prefecture, Japan, Japanese clover occurred in an area that flooded 3 to 7 times/year but rarely experienced flooding of more than 10 days. Japanese clover's distribution was more closely correlated to soil texture than flooding regime or flooding period. Japanese clover occurred on fine-textured soils and was rare or absent on coarse-textured soils. Japanese clover cover was positively correlated with the percent weight of fine soil particles (r =0.78, P<0.001) [108]. Around Cave Run Lake in northeastern Kentucky, Korean clover occurred on mud flats but not on frequently or infrequently flooded sites, and Japanese clover occurred on mud flats and frequently flooded sites [87]. Growing-season flood frequency or duration during the study period was not reported.

Sources and Credits

  1. (c) Harry Rose, some rights reserved (CC BY), https://www.flickr.com/photos/macleaygrassman/10355490153/
  2. (c) Harry Rose, some rights reserved (CC BY), https://www.flickr.com/photos/macleaygrassman/10355282375/
  3. (c) Harry Rose, some rights reserved (CC BY), https://www.flickr.com/photos/macleaygrassman/10355430283/
  4. (c) Harry Rose, some rights reserved (CC BY), https://www.flickr.com/photos/macleaygrassman/10355278923/
  5. (c) Lynn Michael, some rights reserved (CC BY-NC), uploaded by Lynn Michael
  6. (c) Sam Kieschnick, some rights reserved (CC BY), uploaded by Sam Kieschnick
  7. Adapted by Kate Wagner from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Kummerowia_striata
  8. Public Domain, http://eol.org/data_objects/1386496
  9. Public Domain, http://eol.org/data_objects/24629326

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