Bush Clover (Invasive Exotic Plants of North Carolina)

Bush Clover

Lespedeza bicolor

Summary ⁸

Lespedeza bicolor is a species of flowering plant in the legume family known by the common names shrubby bushclover, shrub lespedeza, and bicolor lespedeza. It is native to Asia and it is widely grown as an ornamental plant. In some regions, such as the southeastern United States, it grows in the wild as an introduced and invasive species.

Impacts and control ⁹

More info for the terms: cover, fire management, invasive species, natural, prescribed fire, presence, tree

Impacts: Most predictions and descriptions of bicolor lespedeza's detrimental impacts on vegetation, wildlife habitat, and land management are anecdotal (e.g., [21,28,31,57]). Detailed study and documentation of the impacts of dense bicolor lespedeza stands are lacking. Bicolor lespedeza is most problematic in the southeastern part of the United States. In southern forests from Louisiana and Arkansas east to Virginia and Florida, bicolor lespedeza occupies an estimated 115,550 acres (46,760 ha), of which nearly 50,000 acres (20,230 ha) occurs in Georgia and Arkansas [59]. In Virgina, Kentucky, and Tennessee, bicolor lespedeza is not recognized as a "severe" threat and usually requires a disturbance to establish [48,80,89]. In South Carolina, bicolor lespedeza is considered a "severe threat" to the composition, structure, or function of native vegetation [75]. In Georgia, bicolor lespedeza is a "serious problem" and has replaced native species in wildland habitats [31].

Although bicolor lespedeza impacts were not quantified, several sources indicate that native vegetation, forest regeneration, wildlife habitat, and land management options can be negatively affected in heavily invaded areas. Even an early publication that highlighted the value of bicolor lespedeza for wildlife reported that once established, dense stands (≥50,000 or more shrubs/acre) could prevent grass growth and tree establishment [21]. In a field guide of plants invasive to southern forests, Miller [57] also reports that dense bicolor lespedeza stands prevent forest regeneration and can restrict land access. According to southern silvicultural management guidelines, bicolor lespedeza is "extremely aggressive" in open areas and can replace native vegetation, alter wildlife habitat, and reduce diversity. Because bicolor lespedeza sprouting and spread have been reported after fire (see Plant response to fire), prescribed fire management options in prairies and pine savannas may be limited by bicolor lespedeza's presence [28].

Control: Few studies reported on the best methods to control bicolor lespedeza populations; however, the potential of a persistent seed bank requires long-term monitoring in control areas [57]. General weed control theory suggests that control of biotic invasions is most effective when it employs a long-term, ecosystem-wide strategy rather than a tactical approach focused on battling individual invaders [53]. In all cases where bicolor lespedeza is targeted for control, the potential for other invasive species to its void must be considered [10].

Fire: For information on the use of prescribed fire to control this species, see Fire Management Considerations.

Prevention: Perhaps the best initial step to prevent establishment and growth of bicolor lespedeza in uninvaded areas would be to prohibit seeding or planting in nearby areas. As of 1991, however, bicolor lespedeza was still listed as a northeastern conservation plant useful to wildlife for food and cover [52].

It is commonly argued that the most cost-efficient and effective method of managing invasive species is to prevent their establishment and spread by maintaining "healthy" natural communities 53,72 and by monitoring several times each year [45]. Managing to maintain the integrity of the native plant community and mitigate the factors enhancing ecosystem invasibility is likely to be more effective than managing solely to control the invader [39].

Weed prevention and control can be incorporated into many types of management plans, including those for logging and site preparation, grazing allotments, recreation management, research projects, road building and maintenance, and fire management [86]. See the Guide to noxious weed prevention practices [86] for specific guidelines in preventing the spread of weed seeds and propagules under different management conditions.

Cultural control: No information is available on this topic.

Physical or mechanical control: Heavy and repeated cutting or grazing have been reported to decrease bicolor lespedeza cover [62]; however, timing and duration of these treatments were not described.

Biological control: As of 2010, there were no reports of bicolor lespedeza biocontrols being studied or released. Biological control of invasive species has a long history that indicates many factors must be considered before using biological controls. Refer to these sources: [88,91] and the Weed control methods handbook [84] for background information and important considerations for developing and implementing biological control programs.

Chemical control: Several studies have compared the effectiveness of different herbicides to control bicolor lespedeza. In one report, mowing 1 to 3 months prior to treating with herbicides increased effectiveness [57]. Herbicide treatments and application methods were compared or reported in the following sources: [8,28,57,58]. Some herbicide tolerances are reported by Morisawa [62].

While herbicides can be effective in gaining initial control of a new invasion or a severe infestation, rarely are they a complete or long-term solution to weed management [13]. See the Weed control methods handbook [84] for considerations on the use of herbicides in natural areas and detailed information on specific chemicals.

Integrated management: No information is available on this topic.

Distribution ¹⁰

More info for the terms: natural, reclamation

As of 1998, bicolor lespedeza occurred as an escaped nonnative from Virginia south to northern Florida and west to Louisiana and Kentucky [42]. Although plants also occur as far north as New York, Ontario, Michigan, and Iowa and as far west as Nebraska and Texas [54,61,87], abundance of bicolor lespedeza in natural areas is greatest in the southeastern United States [32,42]. Bicolor lespedeza is native to the temperate areas of China, Korea, and Japan [25,42]. Plants Database provides a map of bicolor lespedeza's distribution in North America.

Bicolor lespedeza was originally introduced to the United States as an ornamental in 1856 [22,25]. Beginning in the 1930s, bicolor lespedeza was promoted and widely planted for erosion control and wildlife conservation [60]. Plants were also used in mine reclamation [35,82]. From the late 1930s through the 1950s, wildlife managers and the USDA Soil Conservation Service in the Southeast began producing and distributing millions of bicolor lespedeza seeds and seedlings annually [60]. In the mid- to late 1930s, 3 to 4 million bicolor lespedeza were planted for gully stabilization [21]. In 1939, a little over 1.2 million bicolor lespedeza were grown on Civilian Conservation Corps camps; by 1950, there were over 50 million seedlings [70]. More than 400 acres (160 ha) were used to produce bicolor lespedeza seed in the early 1940s [21]. Bicolor lespedeza's use in mine site reclamation has occurred as recently as the 1980s in Fairfield, Texas [35]. Eighteen years after planting bicolor lespedeza on a surface coal mine site in Laurel County, Kentucky, researchers considered it "naturalized" and noted spread beyond the planting area [82].

In the 1940s and 50s, the USDA recommended bicolor lespedeza to private land owners to improve northern bobwhite habitat [22]. In the 1940s in Kansas, a nursery was established in Kingman County State Park to produce plants and seed for wildlife habitat improvement [49]. From 1948 to 1953 in Virginia, nearly 7 million bicolor lespedeza plants and 17,000 pounds of seed were planted as an attempt to increase northern bobwhite populations in and around farms [30]. In the 1950s, state agencies in Arkansas distributed 775,000 bicolor lespedeza plants and 2,200 pounds of seed for wildlife improvement [40]. In the 1960s, bicolor lespedeza was planted along a 1.3-mile (2.1 km) stretch of Maryland's eastern shore to increase wildlife and particularly northern bobwhite habitat and food availability [11]. For information on northern bobwhites and their use of bicolor lespedeza, see Birds.

When plantings failed in dry or cold habitats, researchers began developing new strains and cultivars with increased drought tolerance, higher seed production, and earlier ripening dates so that bicolor lespedeza would establish and persist at higher elevations and latitudes [5,12,22]. This topic is also discussed in the Botanical description section.

Sources and Credits

(c) Smithsonian Institution, National Museum of Natural History, Department of Botany, some rights reserved (CC BY-NC-SA), https://collections.nmnh.si.edu/services/media.php?env=botany&irn=10334944
(c) VoDeTan2, some rights reserved (CC BY-SA), https://upload.wikimedia.org/wikipedia/commons/1/11/Lespedeza_bicolorDT1.jpg
(c) Suzanne Cadwell, some rights reserved (CC BY-NC), https://www.flickr.com/photos/scadwell/7857877712/
(c) Steven J. Baskauf, some rights reserved (CC BY), http://bioimages.vanderbilt.edu/baskauf/27877
(c) Steven J. Baskauf, some rights reserved (CC BY), http://bioimages.vanderbilt.edu/baskauf/27872
(c) Miya.m, some rights reserved (CC BY-SA), https://upload.wikimedia.org/wikipedia/commons/c/cf/Lespedeza_ja01.jpg
Hiroyuki0904, no known copyright restrictions (public domain), https://upload.wikimedia.org/wikipedia/commons/6/6e/Lespedeza_of_Houkaiji.jpg
Adapted by Kate Wagner from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Lespedeza_bicolor
Public Domain, http://eol.org/data_objects/24629375
Public Domain, http://eol.org/data_objects/24629357

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Bush Clover

Summary 8

Impacts and control 9

Distribution 10