This description covers characteristics that may be relevant to fire ecology and is not meant for identification. Keys for identification are available (e.g., [32,54,66,92]).
Shrub lespedeza is an erect, multibranched shrub that can reach 10 feet (3 m) tall and wide [25,32,54,60]. Stems from the root crown may have diameters of 1.2 inches (3 cm) [33,57,66]. Shrubs may be less robust in cold climates. Entire shrub lespedeza stems or just the tips can be winter killed, but when the current year's growth survives the winter, plants develop stems that are 1 inch (2.5 cm) or more in diameter [33,65]. Shrub lespedeza leaves are deciduous, alternate, and comprised of 3 oval leaflets that are 0.75 to 2 inches (1.9-5 cm) long. Leaflets are about 2/3 wide as long [25,42,60]. Flowers are about 0.5 inch (1.3 cm) long and occur in 2- to 5-inch (5-13 cm) long racemes. Racemes typically support 5 to 15 pea-like flowers and occur on the upper 2 feet (0.6 m) of stems [25,57]. Legumes are flat, indehiscent, 1-seeded pods that measure up to 8 mm long [54,57,66,79]. Shrub lespedeza does not produce a taproot but develops a "heavy, much-branched root system". Partial excavation of a 4-year-old shrub revealed a dense root system that extended 4 feet (1.2 m) wide and 2 feet (0.6 m) deep. This shrub was likely part of experimental plantings made in Beltsville, Maryland [15].
There may be considerable variation in shrub lespedeza's botanical characteristics. In eastern Asia, shrubs are highly variable and there were probably several Asian introductions to the United States [33]. Shrub lespedeza seeds that came to be known in the US as 'Natob' cultivars were collected from the northwestern Shanxi Province of China where winters are cold and dry and growing seasons are short [15]. United States breeding programs also produced several different shrub lespedeza strains. Strains were often selected for high seed production, retention of ripe fruits, increased winter hardiness, and rapid seed maturation (review by [12]).
As of 1998, shrub 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 shrub lespedeza in natural areas is greatest in the southeastern United States [32,42]. Shrub lespedeza is native to the temperate areas of China, Korea, and Japan [25,42]. Plants Database provides a map of shrub lespedeza's distribution in North America.
Shrub lespedeza was originally introduced to the United States as an ornamental in 1856 [22,25]. Beginning in the 1930s, shrub 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 shrub lespedeza seeds and seedlings annually [60]. In the mid- to late 1930s, 3 to 4 million shrub lespedeza were planted for gully stabilization [21]. In 1939, a little over 1.2 million shrub 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 shrub 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 shrub 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 shrub 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 shrub lespedeza plants and 2,200 pounds of seed for wildlife improvement [40]. In the 1960s, shrub 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 shrub 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 shrub lespedeza would establish and persist at higher elevations and latitudes [5,12,22]. This topic is also discussed in the Botanical description section.
Potential for postfire establishment and spread: There is considerable potential for postfire establishment and spread of shrub lespedeza on burned sites. A handbook that describes silvicultural management guidelines for southern forests and woodlands indicates that shrub lespedeza is promoted by fire. High light levels and soil disturbances encourage establishment [28], and shrubs may sprout from the root crown following fire [46,70]. Population expansion on burned sites was reported by several researchers [28,57,76]. Because shrub 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 shrub lespedeza's presence [28].
Preventing postfire establishment and spread: Preventing invasive plants from establishing in weed-free burned areas is the most effective and least costly management method. This may be accomplished through early detection and eradication, careful monitoring and follow-up, and limiting dispersal of invasive plant propagules into burned areas. General recommendations for preventing postfire establishment and spread of invasive plants include:
For more detailed information on these topics, see the following publications: [2,9,34,86].
Use of prescribed fire as a control agent: In the available literature (2010), use of fire to control shrub lespedeza was not studied and rarely discussed. A silvicultural management handbook reported that prescribed fire is not a control option [28]. However, others suggest that prescribed fire may be useful in controlling shrub lespedeza "under certain circumstances and in and in combination with other control methods", but details regarding circumstances and other control methods were lacking [78]. Morisawa [62] suggests that fire could be used to stimulate germination and deplete the seed bank
Shrub lespedeza is well adapted to survive fire. Seeds are heat tolerant, and several studies report abundant shrub lespedeza seedlings on burned sites. Postfire sprouting is also common following fire. Without additional fire studies, however, it is not possible to address potential differences in fire effects based on fire season or fire severity.
Shrub lespedeza seeds are heat tolerant, and in some studies, seed germination increased with heat exposure. In a Japanese study, 14% of untreated shrub lespedeza seeds geminated. After 1 minute in 190 °F (90 °C) water, germination increased to 78%, and after 3 minutes at 160 °F (70 °C), germination was 84% (Mitsui 1949 cited in [44]). In a US laboratory, shrub lespedeza tolerated 4 minutes of moist-heat treatments of up to 208 °F (98 °C) but failed to germinate after 4 minutes of dry-heat treatments at 210 °F (100 °C). Although seeds may have been killed at 210 °F (100 °C), researchers did not test seeds for induced secondary dormancy. Results of the study are summarized below. Heat treatments were applied in winter and in summer, but differences between treatment seasons are unclear because seed source, seed collection dates, and/or seed storage conditions were not reported [18].
Percent germination of shrub lespedeza seed treated with moist or dry heat for 4 minutes in the winter or summer [18]. Germination of unheated bicolor seeds averaged 64% (based on a very similar study by the same authors presented in another publication) [55]. Temperature (°C) 45 60 70 80 90 98-100 Germination of moist-heat-treated seeds (winter) 62 68 69 35 0 1 Germination of moist-heat-treated seeds (summer) 44 76 68 92 84 88 Germination of dry-heat-treated seeds (winter) 65 69 68 66 54 0 Germination of dry-heat-treated seeds (summer) 44 68 80 100 100 0Optimal conditions for germination of shrub lespedeza seeds were not reported in detail in the available literature. Light is not required for germination, and under laboratory conditions, seed germination may average 76% [12]. Most sources indicate that a proportion of shrub lespedeza seed is hard and requires scarification [15,44,60], although Davison [21] suggests that seeds are "not hard enough to require scarification". Two land management manuals report that fire may scarify and increase the germination of hard, soil-stored shrub lespedeza seed [28,60].
In Japan, researchers found that as many as 85% (Sakamoto 1949 cited in [44]) and as few as 28% (Mitsui and Inoue 1952 cited in [44]) of shrub lespedeza seeds were hard. More mature seed crops typically had fewer hard seeds and higher germination percentages than freshly ripe seed (Iwata personal observation cited in [44]). In a study conducted in Japan, 14% of untreated shrub lespedeza seeds geminated. After 1 minute in 190 °F (90 °C) water, germination increased to 78%, and after 3 minutes at 160 °F (70 °C), germination was 84% (Mitsui 1949 cited in [44]). For more on heat and shrub lespedeza seed germination, see Fire adaptations.
Shrub lespedeza occurs along roads and fences, and in disturbed sites, old fields, clearings, savannas, woodlands, and forests throughout its nonnative range [33,66,73,93]. Shrub lespedeza is much more common in natural areas in the Southeast than in the Northeast or Midwest [20,42,73].
Climate: One source indicates that shrub lespedeza is hardy to USDA zone 4, which suggests a tolerance of temperatures as low as -20 °F to -30 °F (-29 to -34 °C) [25]. Another source indicates hardiness to USDA zone 6, which represents a low-temperature tolerance of -10 °F (-23 °C) [52]. These reports may reflect differences between shrub lespedeza cultivars, some of which were developed to produce seed before first frosts. Reports may also reflect differences in top-kill damage in cold climates (see Botanical description). In the Northeast, shrubs often die back at the branch tips in winter, but winter damage ranges from no visible damage to complete top-kill [26].
Elevation: In a coal mine revegetation guide, planting of shrub lespedeza is not recommended on sites above 2,500 feet (760 m) [90].
Soils: Shrub lespedeza grows and persists on a wide variety of soil types, textures, and fertility levels, but shrub establishment and growth are typically limited on poorly drained soils [22,26,52,70]. Edminster [26] suggests that shrub lespedeza does not grow well on acidic soils, but Evans and others [28] report that shrub establishment occurs on strongly acidic to neutral soils. In a coal mine revegetation guide, use of shrub lespedeza is not recommended on soils with a pH below 4.5 [90]. In a resource management manual, Mitchell [60] indicates that shrub lespedeza grows best on moist to well-drained sandy loams with pH levels of 4.4 to 5.6. Growth was poorer on deep sands, poorly drained lowlands, highly alkaline soils, and extremely eroded soils. After evaluating more than 600 shrub lespedeza plantings in the Southeast, it was apparent that the shrubs grew best in highly fertile, well-drained soils, but several stands occurred along woodland edges with "poor", low-fertility soils [70].
Impacts: Most predictions and descriptions of shrub 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 shrub lespedeza stands are lacking. Shrub lespedeza is most problematic in the southeastern part of the United States. In southern forests from Louisiana and Arkansas east to Virginia and Florida, shrub 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, shrub lespedeza is not recognized as a "severe" threat and usually requires a disturbance to establish [48,80,89]. In South Carolina, shrub lespedeza is considered a "severe threat" to the composition, structure, or function of native vegetation [75]. In Georgia, shrub lespedeza is a "serious problem" and has replaced native species in wildland habitats [31].
Although shrub 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 shrub 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 shrub lespedeza stands prevent forest regeneration and can restrict land access. According to southern silvicultural management guidelines, shrub lespedeza is "extremely aggressive" in open areas and can replace native vegetation, alter wildlife habitat, and reduce diversity. Because shrub 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 shrub lespedeza's presence [28].
Control: Few studies reported on the best methods to control shrub 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 shrub 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 shrub lespedeza in uninvaded areas would be to prohibit seeding or planting in nearby areas. As of 1991, however, shrub 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] (e.g., avoid road building in wildlands [85]) 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 shrub lespedeza cover [62]; however, timing and duration of these treatments were not described.
Biological control: As of 2010, there were no reports of shrub 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 shrub 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.
Shrub lespedeza provides food for deer, rabbits, gophers, northern bobwhites, doves, and livestock and provides habitat or cover for northern bobwhites, doves, and woodcocks [21,22,26,68,70].
Deer: White-tailed deer feed on young shrub lespedeza plants [21,60]. Some indicate that white-tailed deer consider shrub lespedeza palatable [26,70]. Davison [22] suggests that shrub lespedeza is susceptible to "overgrazing" by white-tailed deer.
Small mammals: Rabbits feed on shrub lespedeza leaves, bark, and seeds, but seem to prefer seeds. Roots of shrub lespedeza are eaten by Baird's pocket gophers [40]. In shrub lespedeza border strip plantings in Arkansas, sign left by eastern cottontail was more common than that left by northern bobwhites. In this area, eastern cottontails ate shrub lespedeza bark and leaves [40]. Eastern cottontails observed near Pineville, South Carolina, utilized shrub lespedeza extensively in early winter. When shrub stems were 21 to 59 inches (53-150 cm) tall and had diameters that averaged 0.16 inch (0.4 cm), eastern cottontails often cut the stems to gain access to the seeds. On plants with large stems, bark was eaten, and sometimes stems were girdled [69].
Birds: Shrub lespedeza was often planted to increase northern bobwhite populations in the eastern United States. Although shrub lespedeza seeds are consumed by northern bobwhites, they may not be preferred over native foods, and shrub lespedeza may not provide valuable nesting habitat.
On Maryland's eastern shore, shrub lespedeza was among the top 10 items recovered from the crops of northern bobwhites shot from late November to mid-January [11]. In sandhill vegetation in North Carolina, shrub lespedeza was important in the spring and early summer diets of adult male northern bobwhites. In one year, shrub lespedeza accounted for almost 25% of crop volume, but in another year, it accounted for less than 4%. Researchers did not speculate about the annual differences in use [16]. In shrub lespedeza border strips planted adjacent to crops as a means to improve wildlife habitat in Arkansas, the average annual distance between signs of northern bobwhite use was 0.4 mile (0.6 km), which was less than that for natural borders where the distance was 1.3 miles (2 km). The researcher reported that northern bobwhites used strips primarily for feeding [40]. After reviewing available literature, Davison [23] classified shrub lespedeza as a "choice" northern bobwhite food, which indicated a good-quality, digestible, and nutritious food that was eaten readily when available. The food choice classification was not geographically or seasonally limited.
When evaluating shrub lespedeza plantings on hunting preserves in Alabama and South Carolina, researchers found that although it was a preferred food of northern bobwhites the plantings did not provide valuable nesting habitat. In areas where native northern bobwhite foods were not limited, planting shrub lespedeza did not increase northern bobwhite populations. Often populations concentrated in planted shrub lespedeza stands in the winter, which may have increased their vulnerability to hunters [71]. After 7 million shrub lespedeza plants and 17,000 pounds of seed were planted on Virginia farmlands in the 1940s and 50s, field census surveys conducted in some planting areas revealed "no practical benefits" in increasing northern bobwhite populations [30].
Other bird species that utilize shrub lespedeza include sparrows and juncos that were said to "frequent" stands [21], and American woodcocks that utilize stands for cover (Sepik personal communication and Roberts personal observation cited in [68]). Doves utilized shrub lespedeza stands for food and nesting habitat. Feeding on seeds was "exceptional" after January in Rock Hill, South Carolina, and ground nests were found in stands near Tallahassee, Florida [21].
Livestock: Some report that shrub lespedeza is palatable to and eaten by livestock [26,70]. However, Davison [22] suggests that cattle and horses find shrub lespedeza unpalatable.
Insects: In upland and wet longleaf pine savannas in southern Louisiana and Mississippi, bees were commonly collected from shrub lespedeza shrubs. Fourteen bee species were collected from shrub lespedeza including sweat bees (Lasioglossum spp.), leaftcutter bees (Coelioxys sayi and Megachile spp.), southern carpenter bees (Xylocopa micans), long-horned bees (Melissodes bimaculata), and bumble bees (Bombus spp.) [3]. Because shrub lespedeza flowers in late summer, it can be important to honey bees, which have fewer food sources at this time of year [26].
Many studies report shrub lespedeza on burned sites. Increased abundance and spread of plants on burned sites from sprouts and/or seedlings is common, even on repeatedly burned sites. Although shrub lespedeza is common following fire, more studies are needed to evaluate the effects of fire season and fire severity.
Many sources anecdotally indicate that shrub lespedeza is tolerant of or even promoted by fire. Hunter [40] notes that shrub lespedeza "will withstand .... burning". In guidelines for silvicultural management and weed control, fire is said to "promote" spread of shrub lespedeza [28,57]. During burning operations in slash pine (Pinus elliottii) plantations in Alabama, shrub lespedeza "spread progressively through the influence of fire" and was "showing a disturbing tendency to spread into the woods as a result of regular burning". In a portion of the Alabama Piedmont that burned each February or March for 7 years, shrub lespedeza cover was 0.01% in the unburned and 0.73% in the burned area [76]. In pine-hardwood stands on the Georgia Piedmont, shrub lespedeza occurred on a site burned about every 4 years for the last 30 years but was absent from sites with no prior burning history. Two years after an "intensive" fire in a pine beetle-infested stand in the periodically burned area, the density of shrub lespedeza was 619 plants/ha [6]. Three years following a March prescribed fire in logged loblolly pine (P. taeda) and shortleaf pine (P. echinata) stands on South Carolina's Clemson Experimental Forest, cover of shrub lespedeza was significantly greater (P=0.007) than prefire levels. Thinning reduced forest basal area to 18 m²/ha. The "low-intensity" fire burned when temperatures were 64 to 68 °F (18-20 °C), relative humidity was 22% to 56%, and wind speeds were 2 to 4 miles (4-7 km)/hour. The maximum temperature recorded at 2.6 feet (0.8 m) above ground was 487 °F (253 °C) [64].
While the above studies indicate greater abundance or spread of shrub lespedeza on burned sites, they fail to report whether increases or spread were due to seedling establishment, postfire sprouting, or both. A study conducted in Chinese silvergrass (Miscanthus sinensis) vegetation north of Honshu, Japan, suggests that both sprouting and germination of shrub lespedeza occurred after a late May wildfire. Density of shrub lespedeza was significantly greater on burned than unburned sites within 2 to 4 months of the fire. Researchers reported a greater density of "stocks/area" on burned than unburned sites, but the density of "stocks/root crown" was not different between burned than unburned sites [41]. These findings suggest that seedlings contributed most to increased stem density but also that plants were not top-killed and sprouted after fire.
Several studies report only seedling establishment following fire. In the Hitachi National Forest in central Japan, there were no shrub lespedeza sprouts but abundant seedlings following a March wildfire in Japanese red pine (P. densiflora) stands. Six months after the fire, there were 10.2 seedlings/m² 12 to 16 inches (30-40 cm) tall. Researchers indicated "remarkable population expansion by seedlings" after fire [36]. After a wildfire on 22 April in oak woodlands in northeastern Japan, shrub lespedeza seedlings formed a dense thicket that persisted 3 years. The researcher supposed that germination was promoted by the high soil temperatures and that establishment was promoted by the open conditions created by burning [43].
A study from the Piedmont of South Carolina illustrates that increases in shrub lespedeza on burned sites may not necessarily be caused by fire. In this study, bicolor lespedeza established after a spring fire and also increased in frequency on unburned plots. "Moderate intensity" prescribed fires occurred in loblolly stands in May and consumed up to 50% of surface fuels. The average pre- and postfire frequencies were 0% and 4% on spring-burned plots and 8.7% and 12% on unburned plots, respectively [19]. Findings from this study are also presented in another publication by Cushwa and others [17].
While shrub lespedeza seedlings maybe common on burned sites, postfire sprouting may also contribute to population increases. Kang and Iizumi [46] reported in a review that postfire sprouting often produces dense shrublands on frequently burned demilitarized zones in Korea. Rosene [70] reported that shrub lespedeza produced many root crown sprouts after a winter fire, and on sites with "sufficient fertility", burned plants were "thicker" than unburned plants.
High seed yields have been reported for shrub lespedeza, but droughts and frosts can lead to seed failures. Shrubs generally produce seed once they reach 3 or 4 years old. When shrub lespedeza was seeded on Maryland's eastern shore, they "furnished considerable amounts of seed" by their 4th year [11]. Edminster [26] reports that shrubs "reliably" produce seed at 3 years old and sometimes at 2 years old.
According to a handbook on silvicultural management guidelines for the South, shrub lespedeza can produce as many as 300 million seeds/acre [28]. When grown as a crop, shrub lespedeza produced seed yields of 336 to 447 kg/ha [12]. In some early plantings of shrub lespedeza, ripe seed was not produced before the first frost, which led to seed production failures [24,40]. When seed production was compared in Virginia and North Carolina, production was less in Virginia. Drought conditions during the study period delayed flowering and seed production and made seed more susceptible to frost kill [24]. Through selective breeding, researchers developed the 'Natob' cultivar that produced early-ripening seeds and stems that were more winter hardy. 'Natob' could produce about 350 lbs of seed/acre if the growing season was 145 days or more and if the first frost occurred on or after 25 September [5].
During early plantings of shrub lespedeza stands for wildlife habitat improvement, it became evident that moisture was important for seedling establishment. In the 1950s in Arkansas, shrub lespedeza did not establish well from seed, and after 2 successive dry growing seasons, the majority of planted seedlings had died [40]. A USDA bulletin that encouraged landowners to use shrub lespedeza to improve wildlife habitat and increase northern bobwhite populations recommended planting scarified seed at 0.5 inch (1.3 cm) depths when there was "good" ground moisture [22]. In a later land management publication, soil moisture was noted as critical to germination and establishment. In the Southeast, seeding was not recommended after 15 May [60].
Growth of shrub lespedeza can be rapid. Conservation planting guidelines reported that shrub lespedeza established easily by seed and grew rapidly on "fair to good" sites and "satisfactorily" on "poor" sites. On "good" sites, shrub lespedeza could reach 9 feet (2.7 m) tall in 3 to 5 years and 12 feet (3.6 m) in 5 to 8 years. On "poor" sites, plants may be 6 feet (1.8 m) in 5 years and 9 feet (2.7 m) in 8 years [26].
While shrub lespedeza is tolerant of disturbances and early-seral conditions [4,40,83], shrubs also persist beneath forest and woodland canopies [57,94].
Full sun to dense overstory conditions are described for shrub lespedeza's nonnative habitats. According to the Native Plant Society in Virginia, shrub lespedeza occupies full- and partial-sun sites [89]. A resource management manual indicates that shrub lespedeza tolerates up to 50% shade [60]. In weed management notes published by The Nature Conservancy, shrub lespedeza is reported as shade tolerant [62], and other weed management guides and meeting notes report that shrub lespedeza establishes, reproduces, and spreads successfully beneath moderate to dense canopies [56,57]. However, along Roanoke River Basin transects in North Carolina that extended from the edge of agricultural fields into mixed hardwood forest interiors, shrub lespedeza occurred at the forest edge but was absent from the forest interior [29].
Shrub lespedeza is described in disturbed, early-seral, and mid-seral habitats in its native and nonnative ranges. When shrub lespedeza field border plantings in Arkansas were evaluated, the researcher indicated that field borders tolerated cutting, disking, and burning [40]. In the Prentice Cooper State Forest and Wildlife Management Area of Tennessee, shrub lespedeza was reported only in disturbed areas, which included roadsides, tornado paths, burned areas, pipeline clearings, or ditches [4]. Shrub abundance, however, may be reduced by heavy grazing [22].
In China and Japan, shrub lespedeza grew on early-seral sites impacted by a volcanic eruption and in the forest stage of succession in old fields. Following the eruption of volcano Usu in northern Japan, shrub lespedeza was intentionally seeded for erosion control. Within about 6 years of the eruption, plants were producing seed. The eruption deposited 3 to 10 feet (1-3 m) of volcanic ash and pumice in the study area [83]. When succession from grassland to climax forest communities was evaluated in subarctic to warm-temperate regions of Japan, shrub lespedeza often dominated the shrub stage. Shrub communities followed the pioneer, short-grass, and tall- or perennial grass stages but preceded the pioneer tree and climax forest stages [63]. In the Yancun watershed in Shanxi Province, China, shrub lespedeza was most common in the forest stage of succession that occurred on croplands abandoned 30 to 50 years earlier [94].
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[1][2] 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.[3]
This plant is quite variable in appearance, and it has been bred into a number of cultivars. In general, this plant is an erect shrub growing to 3 metres (9.8 feet) in height and width, generally remaining smaller in cold climates.[3] It can grow from ground level to 5 feet (1.5 metres) in one growing season.[2] The cultivars "Little Buddy" and "Yakushima" grow to 3 feet (0.91 metres)[4] and 1.5 feet (0.46 metres),[5] resp. Lespedeza bicolor grows from a thick root system. The stems may be 3 centimetres (1.2 inches) in diameter. The leaves are each made up of three oval leaflets up to 5 centimetres (2.0 inches) long. The inflorescence is a raceme of up to 15 open pealike flowers,[3] which are pink and purple in color.[2] There are also cleistogamous flowers which self-pollinate and do not open. The fruit is a flat legume pod nearly a centimeter long which contains one seed.[3]
This species was first introduced to the United States as an ornamental shrub in 1856, and it was likely introduced several times after that. In the 1930s it was recommended for use as erosion control and in the revegetation of abandoned mine sites. It was used to enhance wildlife habitat, particularly for the northern bobwhite. The United States Department of Agriculture produced and distributed the seed and many millions were planted. A number of strains and cultivars were developed to improve the plant's drought tolerance and seed production.
It can grow in many types of habitat, including disturbed areas. By the 1990s the plant had escaped cultivation and taken hold in many regions of the eastern United States, especially those in the Southeast. In the US, it is now present from New York to northern Florida and as far west as Nebraska and Texas. It can be found as far north as Ontario in Canada.[3]
In some areas this plant can form dense stands, becoming an aggressive invader.[3] It has been considered threatening in areas where it has disturbed or prevented the growth of native plants, including grasses and trees. It may spread after fire, interfering in schedules of controlled burns of fire-adapted habitat types.[3]
Lespedeza bicolor var. japonica contains lespedamine which is structurally related to DMT[6][7] and dihydrolespedezol derivatives, as well as the dimeric flavonoid, lespebicolin B[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.
