Eragrostis curvula is widely introduced as a forage and ground cover plant and is occasionally found as an escape.
Eragrostis lehmanniana Nees, Fl. Afr. Austr. 402. 1841, is another South African species introduced into Asia as a forage grass. Similar to Eragrostis curvula but differing by having papery basal sheaths with the nerves less prominent and more widely spaced and wiry culms. It has been erroneously reported from Pakistan (viz. A.K. Khan M8) but as it has been introduced into India it may yet be found here.
Botanical description: This description covers characteristics that may be relevant to fire ecology and is not meant for identification. Keys for identification are available (e.g., [8,44,49,123]).
Aboveground description: Weeping lovegrass is a large bunchgrass that is generally a long-lived perennial [3,8,49] but in northern US habitats may be an annual [58]. Weeping lovegrass may reach 75 inches (190 cm) tall, and the basal crown diameter of isolated plants may reach 15 inches (38 cm) [95,123]. Leaf blades are narrow, stiff, finely pointed, and measure up to 26 inches (65 cm) long and 3 mm wide. Leaf blade margins are often rolled inward [8,28,81].
Weeping lovegrass generally produces open, nodding panicles. Inflorescences may measure 16 inches (40 cm) long and 6 inches (15 cm) wide. Spikelets may reach 1 cm long and contain 4 to 15 florets [8,47,123]. Seeds are rather long, up to 1.7 mm, and flattened [8,47,88].
Weeping lovegrass ecotypes and/or cultivars described in the Distribution and Occurrence section typically differ only in leaf size, palatability, "vigor", and/or cold tolerance [23,26]. Cultivars are likely best identified through historical planting records and not through morphological differences.
Photo © James H. Miller, USDA Forest Service, Bugwood.orgBelowground description: Weeping lovegrass produces an extensive thick mat of roots, which have made it useful for erosion control [3,58]. Shoop and McIlvain [95] report that vertical roots may reach 15 feet (4.6 m) deep and spread out 3 feet (1 m) on sandy soils. Roots often fill all the surface soil space between plants. The first roots produced by weeping lovegrass seedlings are large and generally grow straight down; these primary roots develop 30 to 60 fine rootlets per inch of primary root length. Seedling roots grow rapidly; in the first month of growth, weeping lovegrass roots averaged of 0.54 inches (1.4 cm) of growth per day. Maximum seedling root growth in a single day was 2 inches (5 cm). In the field, a 2-year-old weeping lovegrass plant produced 600 to 800 main roots that reached a maximum depth of over 6 feet (2 m) and a maximum lateral spread of over 10 feet (3 m) [27].
Weeping lovegrass is a nonnative species that occupies a relatively large range in the United States. Weeping lovegrass populations are sporadic along the western US coast, in the southern half of the continental states, along the eastern US coast, and in Hawaii and Puerto Rico. In the continental states, populations occur as far north as Illinois and Ohio [8,28]. Weeping lovegrass is most common in Arizona, New Mexico, Oklahoma, and Texas [37,47] but is "becoming common" in New Jersey and Pennsylvania [44]. Generally, weeping lovegrass is most common in those areas where it was intentionally planted. For a map of the scattered weeping lovegrass populations throughout the United States, see the Grass Manual on the Web.
Weeping lovegrass is native to southern Africa [8,123], and several ecotypes from different parts of South Africa were seeded and have become established in the United States [23,26].
Throughout the United States, weeping lovegrass was planted most often for erosion control and livestock forage [37,57,103,123,126]. However, it has also been used as an ornamental [49], in pastures [50], in mine reclamation [80,110], along highways [50,61], and on severely disturbed sites [135]. These topics are discussed more in Management Considerations.
Weeping lovegrass seed introduced to the United States was collected from several different African ecotypes. These ecotypes are recognized as cultivars in the United States. The earliest collection of weeping lovegrass seed, from north-central Tanzania, occurred in 1927. This ecotype ('A-67') was planted and established on 2,000,000 acres (800,000 ha) in Oklahoma and northwestern Texas from 1940 to 1980. Other ecotypes ('Emerlo' and 'Morpha') were collected near Pretoria, South Africa, in the 1940s and 1950s and were introduced in the United States in the 1950s and 1960s. The last ecotype ('Renner') was collected from Lesotho, South Africa, and introduced in the United States in 1972 [23,26]. Ecotypes or cultivars are also discussed briefly in Aboveground description and Site Characteristics.
Weeping lovegrass was first planted in the United States in Stillwater, Oklahoma, in 1935. By 1965, it was growing in New York, and as recently as 1990, weeping lovegrass was seeded in southeastern Arizona. Throughout the southwestern and south-central United States, weeping lovegrass was planted extensively from 1936 to 1945 for erosion control [34]. In the southeastern United States, seeding of weeping lovegrass began in the 1940s. It was planted on a wildlife refuge in McBee, South Carolina, in 1942 (Ingram, personal communication cited in [126]) and on severely eroded, infertile, acidic sites in southeastern Tennessee, beginning in 1941 [29]. Beginning in the 1960s, weeping lovegrass was seeded along highways by the New York State Department of Transportation. Seeding occurred "en masse" in the 1970s and 80s on Long Island Expressway and Sunrise Highway in Suffolk County [61]. After 1988, severely disturbed sites were seeded with weeping lovegrass in Fort Benning, Georgia, [32] and on Kaho'olawe Island, Hawaii [118]. As late as 1990, areas burned by a July wildfire in southeastern Arizona were seeded with weeping lovegrass. By 2002, weeping lovegrass monocultures had established to the virtual "exclusion of other native graminoids and forbs" [78]. The use of weeping lovegrass in revegetation and the potential for these projects to contribute to its spread are discussed more in Introduction and spread.
Potential for postfire establishment and spread: Weeping lovegrass can establish from seed on burned sites [15,78]. Although weeping lovegrass seed dispersal is limited, if stands occur near burned sites, there is high potential for establishment on burned sites. In recent years, weeping lovegrass has been intentionally seeded on burned sites [78] and in other revegetation efforts [32,118], making it virtually impossible to control weeping lovegrass populations and spread in these areas.
Preventing invasive plants from establishing in weed-free burned areas is the most effective and least costly management method. This can be accomplished through early detection and eradication, careful monitoring and follow-up, and limiting dispersal of invasive plant seed 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: [6,14,46,107].
Prescribed fire as a control agent: Prescribed fire is not a likely control agent for weeping lovegrass. Establishment of weeping lovegrass is often increased by removal of litter. However, fire frequencies at less than 5-year intervals may damage plants [43], although this did not occur in South Africa [42]. During fire studies designed to determine how best to use fire to encourage weeping lovegrass growth, a researcher found that summer and winter fires can decrease productivity and late-spring fires may kill seedlings. Plant damage was most likely when soils in weeping lovegrass stands were dry and litter had built up in plant crowns [34].
Weeping lovegrass may experience high fire frequency in its native and nonnative habitats. In the 900-km² Hluhluwe-Umfolozi Park dominated by weeping lovegrass in northern Kwa-Natal, South Africa, the average fire-return interval is 3.8 years. Fire frequency depends largely on fire management policies but also depends on fuel loads, which depend on rainfall. Fire frequency and size were evaluated from 1,111 fire records from 1956 to 1996. In the Park, all but 1 study site had a fire-return interval of 4 years or less. On average, 26% of the park burned each year, and fire size averaged 9.1 km². In the 40-year period, less than 1% of the Park burned only once and another 1% burned more than 20 times. Most fires were ignited by park staff in spring. There were only a few lightning fires and those burned in the summer. Larger areas burned in wet than dry years due to increased grass fuel loads, which increased fire spread potential [5,7].
Before European settlement and the introduction of weeping lovegrass in the Great Plains region of the United States, level to rolling grasslands may have burned every 5 to 10 years and areas with rougher topography may have burned every 20 to 30 years. In the Great Plains, where weeping lovegrass has now been widely introduced, "big" fires tend to occur in drought years that follow at least 2 years of above-average precipitation. If fuels are abundant and continuous, wind speeds and air temperatures are high, and relative humidity is low, fires may spread many miles. Several factors associated with European settlement, such as heavy grazing and cultivation, decreased the fuel availability and fuel continuity in desert grasslands and led to decreased fire frequency [109,132]. Introduction of nonnative grasses, however, may have had the opposite effect on fuel availability, fuel continuity, and possibly fire frequency.
Although no studies directly measure fuel or fire behavior differences between weeping lovegrass-dominated and native-dominated desert grasslands, several studies report on stand structure, development, and growth differences between lovegrasses and native grasses that could influence fire behavior and FIRE REGIMES. Stand structure is often different in native-dominated and lovegrass-dominated grasslands. Lovegrass-dominated grasslands are dense and capable of supporting fire spread, while native grasses are generally discontinuous and less conducive to fire spread [90]. Several researchers have noted increased weeping lovegrass seed production and plant abundance on burned sites [59,68,74,84], which a review [90] reports is rare for native desert grassland species. The review suggests that postfire increases in plant abundance and reproduction could support increased fire frequencies. Given these differences in native- and lovegrass-dominated grasslands, fire frequencies may increase and fire behavior may be different with increased abundance of nonnative lovegrasses.
Along highways near Perth, Australia, sclerophyll woodlands where weeping lovegrass is common burned at 10- to 20-year intervals. Ten-year fire-return intervals were most common (van der Moezel and others 1987 as cited in [79]).
See the Fire Regime Table for further information on FIRE REGIMES of vegetation communities in which weeping lovegrass may occur. Find further fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find FIRE REGIMES".
Researchers have noted weeping lovegrass persistence on annually burned sites [42,74,119], suggesting that fine fuel production is sufficient to carry annual fires in weeping lovegrass stands. Litter is "pronounced" in weeping lovegrass monocultures [36] and accumulates in and around the base of weeping lovegrass plants and around weeping lovegrass root crowns the longer stands are undisturbed [27].
Fire behavior in nonnative habitats: Fire behavior has been described in weeping lovegrass stands in Texas and in velvet mesquite (Prosopis velutina)-desert grasslands in southern Arizona. Fire behavior varied widely during spring prescribed fires (24 head fires and 12 backfires) in weeping lovegrass stands in north-central Texas. Fireline intensity ranged from 75 to 4,706 btu/ft/s. Fuel consumption varied by a factor of 2, and rate of forward spread varied by a factor of 40. In the spring, a minimum total fuel load of 3,308 kg/ha was necessary for successful fire spread. Successful fires spread at 0.3 to 2 miles (0.04-3.4 km)/hour. During the fastest fire, the air temperature was 88 °F (31 °C), relative humidity was 14%, and wind speed averaged 45 km/hour [18,19]. Researchers evaluated fire behavior following a 2002 wildfire in velvet mesquite-desert grasslands in the Sonoita Valley of southern Arizona, where large areas are dominated by weeping lovegrass. The fire burned from 29 April to 2 May when the air temperature was 81 °F (27° C), wind speed averaged 30 to 37 miles (50-60 km)/hour, and relative humidity was less than 10%. Using computer modeling and information from burned sites, researchers estimated that the fire produced scorch heights of up to 200 feet (60 m) and a fireline intensity of up to 7,500 kW/m [60].
Weeping lovegrass seeds germinate best when temperatures are warm, seeds are on the soil surface, and/or after 2 consecutive days of moisture. Seeds germinate in light or dark conditions. Germination of weeping lovegrass on burned sites or following high temperature or smoke treatments is discussed in Fire adaptations and plant response to fire.
Temperature and light: Increased temperatures are typically associated with increased weeping lovegrass germination. After 12 days in controlled conditions, germination of weeping lovegrass was 2% to 96% at temperatures of 59 to 86 °F (15-30 °C). Germination of the 2 weeping lovegrass cultivars increased with each 3-degree increase in temperature [67]. Weeping lovegrass seeds collected from New South Wales, Australia, failed to germinate at alternating temperatures of 36 and 50 °F (2/10 °C). Germination was 69% to 91% when temperatures alternated between 63 and 100 °F (17/40 °C) and 45 and 68 °F (7/20 °C). Germination was best (91%) at alternating temperatures of 68 and 100 °F (20/40 °C) [70]. Weeping lovegrass seed failed to germinate in the greenhouse when soil temperatures were 100 °F (38 °C) [125], suggesting that there are minimum and maximum soil temperature thresholds for weeping lovegrass germination. In other studies, researchers estimated that weeping lovegrass germination requires temperatures above 51.4 °F (10.8 °C) [54] and that dormancy may be induced after 1 to 2 weeks with partial darkness and temperatures below 64 °F (18 °C) [112].
The importance of light in weeping lovegrass germination decreased with increased storage time for seeds collected in Wagga Wagga, Australia. About 50% of seeds germinated immediately after harvest; the rest germinated within a month of harvest. Although germination was generally better in the light than in the dark, after 56 months of storage, weeping lovegrass germination was 56.5% in the light and 57.5% in dark [70].
Burial: During field studies, weeping lovegrass seed on the soil surface germinated best [25]. Thick litter and burial by more than 2 inches (5 cm) of soil may severely limit emergence [33]. In silty clay loam and sandy loam soils in southeastern Arizona, weeping lovegrass seedling emergence decreased with increasing planting depths. Emergence was 71% for seed on the soil surface, 47% at 0.2-inch (0.5 cm) depths, and 24% at 0.8-inch (2 cm) depths. Emergence was greater in sandy loam than in silty clay loam [25].
Moisture: Greenhouse and field studies suggest that the amount of moisture may not be as important as duration of moisture to weeping lovegrass seed germination. In the greenhouse, 2 consecutive days of moisture were required for emergence when soil temperatures were 75 or 86 °F (24 or 30 °C). Emergence rate decreased as the number of dry days between moisture applications increased (r² =0.88 at 86 °F (30 °C) and 0.99 at 75 °F (24 °C)), and earlier emerging seedlings survived longer than later emerging seedlings. In the field in Garza County, Texas, weeping lovegrass failed to emerge from dry sandy soils 10 days after 11 mm of rain, but seedlings did emerge after 2 consecutive days of rain (19 mm total) [125]. In West Texas when the temperature was 75 °F (24 °C), 2 consecutive days of at least 0.6 inch (15 mm) of moisture were required for weeping lovegrass germination of at least 50%. Once seedlings emerged, additional moisture was required within 2 days for seedlings to survive at least 7 days [124].
Laboratory studies found decreases in weeping lovegrass seed germination as soil water potential decreased; however, results of these studies are difficult to compare due to differences in methodology. When weeping lovegrass seeds were planted in clayey soil and incubated at 70 °F (21 °C), emergence was 46% at a soil water potential of -0.03 MPa, and 39% when the soil was drier (-0.3 MPa soil water potential) [131]. Germination of weeping lovegrass seeds collected from New South Wales, Australia, decreased as water potential decreased. Seeds were placed on filter paper moistend with deionized water mixed with varying amounts of polyethylene glycol to adjust water potential. Weeping lovegrass germination rates were approximately 70% at a water potential of -0.5 MPa, 20% at -1.0 MPa, and 0% at -1.5 MPa [70].
Weeping lovegrass is described most often along roadsides, near gardens, in pastures and fields, on disturbed sites, and at forest and woodland edges throughout its nonnative US range [8,28,49,88,133,134].
Climate: In weeping lovegrass' native African range, average monthly minimum and maximum temperatures are 50 to 64 °F (10-18 °C) and 77 to 86 °F (25-30° C), respectively. Winters are cold and dry, and annual precipitation averages 20 to 47 inches (500-1,200 mm). More than half of annual precipitation falls during the growing season [26].
Several rangeland revegetation guides provide a range of low temperature and precipitation tolerances for weeping lovegrass. In a review, Crider [27] reports that closely packed basal stems provide substantial protection of meristems from cold temperatures and droughts. Others report that hard freezing in late April or early May can cause weeping lovegrass mortality [95]. Some report that plants do not persist in areas where temperatures often fall below 0 °F (-18 °C) [33], although plants may survive -11° F (-24 °C) in soils with "adequate" moisture [52]. Seeding guidelines for desert grasslands in southern Arizona, suggest that weeping lovegrass seeding success and persistence are best on sites receiving at least 18 inches (460 mm) of precipitation annually [4]. Weeping lovegrass is unlikely to persist on sites receiving less than 15 inches (380 mm) of annual precipitation [30]. It is possible that temperature and precipitation minimums for weeping lovegrass survival vary among different ecotypes or cultivars. Alderson and Sharp [3] reported that the 'A-67' cultivar is more cold tolerant than other cultivars and grows best where annual precipitation exceeds 14 inches (350 mm). Cultivar 'A-84' grows on sites receiving at least 12 inches (300 mm) of annual precipitation.
In the United States, weeping lovegrass is most productive on sites where minimum and maximum temperatures average 32 to 86 °F (0-30 °C) and summer precipitation averages 16 to 39 inches (400-1,000 mm) [23,26]. However, in Beltsville, Maryland, weeping lovegrass plants were not injured by low temperatures of -16 °F (-27 °C), and plants survived temperatures of -20° F (-29 °C) near Deansboro, New York. In "heavy" soils in Woodward, Oklahoma, though, plants were winter killed at temperatures of 0 °F (-18 °C) [27].
Elevation: In East and South Africa, weeping lovegrass occupies sites between 2,300 and 5,740 feet (700-1,750 m) [26]. In the United States, weeping lovegrass occurs from sea level in the East to over 7,000 feet (2,100 m) in the Southwest [8,119]. Weeping lovegrass occurs at elevations below 1,600 feet (500 m) in California [49], at less than 4,990 feet (1,520 m) in Utah [123], and at elevations of 2,850 to 3,770 feet (870-1,150 m) in the Grand Canyon region [101]. In western Oklahoma and northern Texas, weeping lovegrass occurs at 1,000 to 3,300 feet (300-1,000 m) [26].
Soils: Weeping lovegrass grows best in well-drained, relatively fertile, nonsaline, sandy to clay loam soils [27,33]. It does not tolerate standing water [27].
Most often weeping lovegrass occurs in sandy soils [47,88]. In a greenhouse, weeping lovegrass seedling emergence was greatest from sandy loam (54%) when compared to Pima silty clay loam (47%) and Sonoita silty clay loam (22%). The clay of the Pima soils was 60% montmorillionite and for the Sonoita soils was 80% kaolinite [25].
Weeping lovegrass tolerates salinity and a wide pH range. A review reports that weeping lovegrass is very salt tolerant [129], and in a short-term greenhouse study, weeping lovegrass production after 20 days of treatments with 180 mol NaCl/m³ was 82% of that of nonsaline treatments [93]. In loamy soils in Garza County, Texas, weeping lovegrass grew in areas with a pH of 8.4 [69], and in a controlled study, researchers found that weeping lovegrass seedling growth was not reduced at pH 4 but was reduced at pH 3 [39].
Introduction and spread: Because weeping lovegrass establishes easily and grows rapidly on harsh sites, it was seeded or planted on mine spoils, along roadsides, active sand dunes, and severely disturbed sites nearly throughout the United States. In some seeded areas, weeping lovegrass has not spread far from its introduction site, but in others, it has expanded its range into natural and sometimes sensitive habitats. Site characteristics that allow for or promote weeping lovegrass spread were not described in the available literature as of 2009.
Mines: Weeping lovegrass can rapidly provide ground cover on mine sites. It tolerates extremely acidic soils and the presence of many heavy metals. Some report that weeping lovegrass escapes easily from mine sites [8], while others indicate that it "gradually gives way to other perennial species" [111]. On abandoned manganese mine lands in southwestern Virginia and northeastern Tennessee, weeping lovegrass cover was considered excellent soon after seeding. These mines were a major source of nonpoint source water pollution, which weeping lovegrass helped to decrease [80]. On a coal mine spoil in southeastern Kentucky, weeping lovegrass provided most of the early cover, but 3 to 4 years after seeding, tall fescue (Schedonorus arundinaceus) and lespedeza (Lespedeza spp.), which were also seeded, dominated the site and were "crowding out" weeping lovegrass [110]. When topsoil collected from a mixed-deciduous forest was used in the revegetation of a mine spoil in Campbell County, Tennesse, Wade [115] found that subsequent seeding of nonnative species such as weeping lovegrass decreased the success of native species emerging from the top soil.
Roadsides: The New York State Department of Transportation planted weeping lovegrass along Long Island highways from the 1960s through the 1980s. As of 2000, weeping lovegrass has become established on dry sandy soils in Suffolk County. It has formed monocultures in late-seral old fields and occurs in maritime grasslands in Shinnecock Hills, which are considered a globally rare ecosystem by the New York Natural Heritage program [61].
Unstable sand dunes: During mismanagement of sandy sites in Vermont, trees and other vegetation were removed. Because the sand was actively moving, these sites proved exteremely difficult to revegetate. After many seeding and planting failures, researchers in the 1940s planted weeping lovegrass on these sites. Weeping lovegrass grew rapidly and produced a thick mat of roots [58].
Severely disturbed site: Although not intentionally planted, weeping lovegrass established and produced greater than 1% cover after a seed mix was used in the interior of Hawaii's severely disturbed Kaho'olawe Island in 1988. Weeping lovegrass was likely a contaminant in the seed mixture. Kaho'olawe Island has a long, severe land-use history that includes island warring, slash-and-burn agriculture, overgrazing, and military training. It is the windiest Hawaiian island and receives only 20 inches (500 mm) of annual precipitation. As of 1916, about 30% of the island was "completely denuded", up to 1 foot (3 m) of topsoil was lost, and in the study area, plant cover was less than 2% [118]. During a second revegetation phase in 1990, researchers intentionally seeded weeping lovegrass, which averaged 17% cover by 1996 [135].
Reports vary regarding weeping lovegrass' potential to spread from its introduction site. In a 1988 review, Cox and others [26] report that weeping lovegrass "does not actively colonize adjacent nonplanted sites". In the Apache Highlands ecoregion of Arizona and northern Mexico, the distribution of weeping lovegrass in 2005 approximated the area where it had been seeded in the 1930s [38]. On the Appleton-Whittell Research Ranch in Arizona, weeping lovegrass that was seeded in 1949 had not spread "far beyond" where it was originally seeded by 1999 (Bock, personal communication cited in [76]). Although weeping lovegrass was planted along roadsides for erosion control in the Carolina Sandhills National Wildlife Refuge, it had not invaded native plant communities there as of 1998. The planting date was not reported [116]. When weeping lovegrass was seeded on bare, severely eroded sites with infertile, strongly acid subsoils in southeastern Tennessee in the 1940s, the researcher noted that it was "expected to persist and develop greater density, but not to spread beyond the seeded area" [29]. In a 2002 publication, Stevens and Ayers [101] report that weeping lovegrass has "recently erupted" along the Colorado River in the Grand Canyon region, and in a 1982 review, Wasser [119] reports that weeping lovegrass has a "strong competitive ability" and may become "weedy without management".
Impacts: Rapid emergence and establishment imply that weeping lovegrass may negatively impact associated vegetation. Persistence of weeping lovegrass suggests that wildlife impacts are possible as well. Following a controlled study, researchers considered weeping lovegrass an "aggressive" species because of its rapid emergence compared to 11 predominantly nonnative grasses and legumes. In a greenhouse study, weeping lovegrass emergence was high at both 70 °F (21 °C) and 82 °F (28 °C) and reached a maximum 1 to 4 days after seeding. Of the 11 species tested, only weeping lovegrass emerged by day 2 at 70 °F (21 °C) [131]. However, in another greenhouse study, weeping lovegrass seedlings averaged only 3 mg of dry weight 90 days after seeding. This growth was much lower than that of other nonnative pasture species such as subterrranean clover (Trifolium subterraneum), common tussock grass (Poa labillardieri), and bulbous canarygrass (Phalaris aquatica), which averaged 18 to 78 mg of dry weight [16]. After multiple studies of planting, growing, and grazing weeping lovegrass, Dalrymple [33] considered established weeping lovegrass plants "very competitive to weedy competition".
Vegetation: Several studies conducted on the Appleton-Whittell Research Ranch in Arizona indicated lower vegetation diversity in lovegrass (Lehmann lovegrass and weeping lovegrass) stands than in native grasslands or shrublands. During a study in 1984, researchers found that cover of native blue grama, native plains lovegrass (Eragrostis intermedia), native forbs, and native shrubs was significantly (P<0.05) greater in areas without lovegrasses. Forb richness and shrub density were also significantly (P<0.05) greater in areas without lovegrasses [12]. In a 1999 study, researchers compared plant species richness in oak (Quercus spp.) savannas, native grasslands, and weeping lovegrass stands. In oak savanna plots, total plant species richness was as high as 134, in native grassland plots was 100, and in weeping lovegrass plots was 58. Native species dominated all plots; there were only 4 nonnative species in all plots. Researchers suggested that superior competitive ability, allelopathy, or earlier initiation of growth in weeping lovegrass could explain the absence of many species from weeping lovegrass plots [76]. When seed banks were compared in burned weeping lovegrass stands and native grasslands in the same area, total seed bank density and seed bank richness were greater in native than in weeping lovegrass grasslands [77].
Wildlife: Several birds and small mammals utilize weeping lovegrass habitats, but often use is lower in weeping lovegrass than in native habitats. Areas seeded to weeping lovegrass in Texas as part of the conservation reserve program to reduce soil erosion are considered important habitat for arthropods, which are important to grassland birds [75]. On the Appleton-Whittell Research Ranch in Arizona, total grasshopper abundance was 44% lower in lovegrass-dominated than in native grasslands, but the largeheaded grasshopper (Phoetaliotes nebrascensis) was significantly (P<0.02) more abundant in lovegrasses than in native grasses [12]. The importance of weeping lovegrass to insects is discussed more in Insects.
On the 3-Bar Game Management Area on the Tonto National Forest, breeding bird species richness and density were greatest in willow (Salix spp.)-dominated riparian sites, followed by chaparral vegetation. Lovegrass-dominated grasslands supported the lowest breeding bird species richness and diversity [105]. On the Appleton-Whittell Research Ranch, total bird counts in lovegrasses were about half those in native desert grasslands (P<0.001). Scaled quail, northern mockingbirds, loggerhead shrikes, Cassin's sparrows, Brewer's sparrows, vesper sparrows, grasshopper sparrows, and eastern meadowlarks were all significantly (P<0.01) more abundant in native grasslands than in lovegrass-dominated grasslands. However, Botteri's sparrow preferred lovegrass habitats [11].
Most rodent species on the Appleton-Whittell Research Ranch were significantly more abundant in native grasslands than in lovegrass-dominated grasslands (P<0.05), although the most common rodent, the hispid cotton rat, was significantly more abundant in lovegrasses than in native grasses (P<0.001) [12]. For more on animal use of weeping lovegrass, see Importance to Livestock and Wildlife.
Control: As of 2009, very few references provided information on the control of weeping lovegrass. On sites where weeping lovegrass was introduced to reduce erosion potential its removal may lead to increased erosion. At Arizona's Tonto National Monument, removal of weeping lovegrass would likely trigger erosion, so Phillips [85] suggested mowing or clipping plants to deplete the seed bank, while seeding native species to promote the replacement of weeping lovegrass by native species.
Fire: For information on the use of prescribed fire to control weeping lovegrass, see Fire Management Considerations.
Prevention: 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 [64,94]. This may be best done by discontinuing the use of weeping lovegrass on disturbed or burned sites. Managing to maintain the integrity of the native plant community and to mitigate the factors enhancing ecosystem invasibility is likely to be more effective than managing solely to control the invader [51].
Cattle and deer feed on weeping lovegrass in its nonnative US range. Several small mammals and birds utilize weeping lovegrass habitats, although species richness and abundance may be higher in native grasslands than in weeping lovegrass stands.
Cattle: Most researchers indicate that cattle graze weeping lovegrass primarily in the spring. In Arizona, cattle preferred weeping lovegrass over associated native grasses in the spring [53]. Hoover and others noted that weeping lovegrass was eaten "readily" by cattle in the spring but eaten "sparingly" in the summer [52]. Diggs and others reported that weeping lovegrass was not grazed by cattle when more palatable species were available, but noted that when more palatable species were not available, weeping lovegrass may be grazed nearly to ground level [37]. Cattle can become tender footed if made to walk on the hard stubble that remains in heavily grazed weeping lovegrass stands (Standford, personal communication cited in [37]). See also Palatability and nutritional value.
Deer: In the winter in the southeastern United States, white-tailed deer feed "considerably" on weeping lovegrass [34].
Small mammals: In a near monoculture of weeping lovegrass in Lynn County, Texas, researchers captured 8 small mammal species. Captures of deer mice and hispid pocket mice were most common in areas with low (30-36%) weeping lovegrass cover, and captures of hispid cotton rats and western harvest mice were most common in areas with high (56-69%) weeping lovegrass cover [35]. In the Appleton-Whittell Research Ranch in Arizona, most rodent species (western harvest mice, hispid cotton mice, and northern pygmy mice) were significantly (P<0.05) more abundant in native grasslands than in nonnative lovegrass stands. However, the most abundant rodent, the hispid cotton rat, was significantly (P<0.001) more abundant in lovegrass stands than native grasslands [12].
Birds: Southwestern bird species were often rare in weeping lovegrass stands or preferred native grasslands over weeping lovegrass stands. Although most bird species were more abundant in native desert grasslands than in lovegrasses on the Appleton-Whittell Research Ranch, Botteri's sparrow was counted more often in lovegrass stands than in native desert grasslands (P<0.001) [11]. Bird nest densities were low in weeping lovegrass stands in central Lynn County, Texas, relative to native grasslands. Researchers located Cassin's sparrow, mourning dove, and common nighthawk nests. Drought conditions (33-57% below average precipitation) prevailed during most of the study [82]. In the southern High Plains of Texas, the grasshopper sparrow was abundant in weeping lovegrass stands [106].
Insects: Weeping lovegrass stands support diverse, abundant, and rare insect populations throughout its southeastern and south-central US range. In Oklahoma, Elateridae and carbid beetles foraged in the "pronounced" litter layer in weeping lovegrass monocultures [36]. In a weeping lovegrass field on the Texas Tech University Farm, researchers found a variety of arthropod families and species utilizing weeping lovegrass habitats [86]. During several entomological surveys in the southern United States, researchers collected a diversity of insects in weeping lovegrass stands. Seldom collected cinch bug (Blissus minutus) adults and nymphs were collected often from weeping lovegrass plants in Florida, Georgia, North Carolina, South Carolina, Oklahoma, and Texas, although this cinch bug was only previously known from Florida. Another rarely collected cinch bug (Toonglasa umbrata) was collected often in weeping lovegrass plants in Arizona, New Mexico, Oklahoma, and Texas [128]. A seed bug (Ligyrocoris slossoni) was collected from dead weeping lovegrass stems in Lake County, Florida. This seed bug was last collected in the 1940s [127]. Plant hopper (Amycle vernalis, Cyrpoptus belfragei, C. reineckei, and Rhynchomitra microrhina) nymphs were collected from weeping lovegrass in the southeastern and south-central United States. Researchers noted that insect use of weeping lovegrass as food and habitat may be relatively recent [130]. During studies in the Southeast, rarely collected turtle bugs (Oncozygia clavicornis and Allopodops mississippienses) were found on weeping lovegrass. The researcher noted that dense weeping lovegrass crowns likely offered insect protection. These turtle bugs represent monotypic genera that may or may not be rare. Little information is available on the ecology or abundance of these insects [126].
Palatability and nutritional value: Although the palatability and forage quality of weeping lovegrass typically decrease as plants approach maturity [95], as the growing season progresses, or during drought conditions [27], management activities may improve or maintain palatability and/or nutrition. Some suggest that grazing and fire can be used to maintain weeping lovegrass palatability. Management guidelines for maximum production and livestock weight gains are provided by Dahl and Cotter [30]. At the Texas Tech University Research Farm, cattle utilization and crude protein of weeping lovegrass were greater on winter- or spring-burned than on unburned plots [59]. Crude protein content was greater and neutral detergent fiber was lower on spring-burned than unburned sites for nearly all of the first postfire season in Texas [72]. On other sites in Texas, weeping lovegrass crude protein and digestibility were greater on clipped than unclipped vegetation 30 days after clipping [66].
Weeping lovegrass palatability and nutrition can vary by ecotype or cultivar [26]. For more on the palatability and nutrition of weeping lovegrass, see the review by Crider [27]. For information on the forage quality of weeping lovegrass cultivars harvested at different times, see Voight and others [114].
Cover value: Weeping lovegrass was often introduced into the United States to reduce soil erosion along roadsides, in overgrazed grasslands, and on severely disturbed sites. This topic is discussed more in the Distribution and Occurrence and Introduction and spread sections. Weeping lovegrass monocultures are said to provide excellent cover for rabbits and better-than-average cover for quail (review by [34]). However, Abbott and others [1] reported that weeping lovegrass stands on the southern High Plains of Texas, "appear to have limited value for wildlife", especially quail, because stands typically lack woody vegetation.
In the south-central United States, weeping lovegrass produces green growth 2 to 4 weeks before most native grasses. Growth begins in the spring when minumum temperatures exceed 50 °F (10 °C) [26,34]. In Woodward, Oklahoma, weeping lovegrass produced some green growth in March, but growth was slow until April [95]. In Oklahoma, weeping lovegrass may be green as late as mid- to late November [34].
Weeping lovegrass flowering dates are earliest in the eastern United States (April-June) [21,88]. In the central United States, weeping lovegrass typically flowers from May to August [37,47], which is earlier than the flowering dates reported for the western United States (July-October) [28,81]. Additional information on seasonal development is presented in Seed production.
Prolific and early seed production is common in weeping lovegrass stands. Given favorable climate and site conditions, weeping lovegrass may flower in its first year [95]. During studies conducted in Oklahoma, established and actively managed weeping lovegrass stands occassionally produced 2 seed crops per year: a large crop in late June and a much smaller crop in September or October. These stands were fertilized and irrigated [2]. Weeping lovegrass panicles may produce 300 to 1,000 seeds [27]. Information on flower production by first-year plants is also presented in Seedling growth.
Several factors may affect weeping lovegrass seed production, although quantitative information on this topic is sparse, and studies were often conducted in actively managed stands. Shade can decrease seed production [34]. Moist conditions and/or high nitrogen levels may increase seed production [2]. In a review, Crider [27] suspects that high humidities and high temperatures may limit seed production, because weeping lovegrass seed crops in southern Texas and southern Florida are typically small. High temperatures and low humidities or low temperatures and high humidities are thought to increase seed production, because seed production is often high in the southwestern United States and the Pacific Northwest. Increased moisture and soil fertility are also associated with increased weeping lovegrass seed production. In Woodward, Oklahoma, weeping lovegrass produced 320 to 450 lbs of seed/acre on an irrigated site and 60 to 140 lbs of seed/acre on a nonirrigated site. On poor, badly eroded soils, just 50 to 100 lbs of seed/acre was produced [27].
Seedling establishment and plant growth: Several anecdotal references report that weeping lovegrass establishes easily from seed and that seedlings show "strong vigor" and provide ground cover rapidly [4,52]. Seedling survival and growth may be reduced in clay soils, drought conditions, and by interference from other species.
Seedling survival: Weeping lovegrass seedling survival in field studies varies widely. Nearly 3 years after summer transplanting of 9-week-old weeping lovegrass seedlings in a Sonoran Desert mixed shrubland in southeastern Arizona, survival averaged 22% [24]. Two years after 6- to 8-week-old weeping lovegrass seedlings were planted in southern Australia sites, survival averaged 92.9%, even though conditions were "very hot and dry" at many sites in the second year. Although survival was high, recruitment was low [120]. In the laboratory, germinated weeping lovegrass seeds did not survive 3 days on dry filter paper [40].
Seedling growth: In the greenhouse, weeping lovegrass seedling dry weight averaged just 3 mg, 90 days after seeding. This growth was much slower than that of other nonnative pasture seedlings, including subterrranean clover (Trifolium subterraneum), common tussock grass (Poa labillardieri), and bulbous canarygrass (Phalaris aquatica), which averaged 18 to 78 mg [16].
Weeping lovegrass seedling development and flowering can vary with site conditions. In west Texas, weeping lovegrass seedling establishment was classified as "good" on sandy soils, "fair" on silty soils, and "poor" on clayey soils [31]. Weeping lovegrass growth and reproduction were better on fine loams than on fine sands when 3 sites in Texas were compared. Seedling growth and reproduction were lowest in Garza County, although annual precipitation was greatest at this site (see table below). Researchers noted that poor seed bed preparation and competition from coastal sandbur (Cenchrus spinifex) plants limited weeping lovegrass growth in this area [65].
Canopy growth and flower production by 1-year-old weeping lovegrass plants on 3 Texas sites (values are averages for 2 planting years) [65] County Soil texture Annual precipitation for the study period (mm) Leaf canopy height (cm) Flower production (number/m) Garza fine sand 564 10.2-28.7 0.5-1.2 Lubbock fine loam between 377 and 564 33.9-50.3 22.8-23.7 Terry loamy fine sand 377 33.7-42.9 4.3-6.8In a follow-up study in Garza County, field densities of up to 65 coastal sandbur plants/m² did not affect weeping lovegrass seedling survival for up to 6 months after seeding. Presence of coastal sandbur, however, did significantly (P<0.05) reduce herbage and seed head production of weeping lovegrass [69].
Weeping lovegrass herbage and seed head production with increasing density of coastal sandbur in Garza County, Texas [69] Coastal sandbur density (plants/m²) Lovegrass herbage yield (g/m²) Lovegrass seed head density (number/m²) 0 194a 8.0a 30 68b 0.8b 45 55b 0.6b 65 41b 0.5b Means with different letters within a column are significantly different (P<0.05)In a greenhouse study, extracts of coastal sandbur and sand shinnery oak (Quercus havardii) did not significantly affect weeping lovegrass germination percentages or seedling shoot growth but did significantly (P<0.05) reduce weeping lovegrass seedling root growth. Extracts of coastal sandbur litter reduced seedling root growth 21% compared to the control, while sand shinnery oak extracts reduced root growth by 92% [69].
In its native African grassland habitats, weeping lovegrass is most common in the seral stage just before "climax" in East and South Africa [30]. A review describes grassland succession in South Africa. Initially sites are colonized by "weedy" vegetation, which is then replaced by short-lived perennials, which are replaced by short-lived grasses. In the next successional stage, the long-lived grass stage, weeping lovegrass is common, until its eventual replacement by the climax red grass (Themeda trianda). After top-killing disturbances, such as fire, in the climax grassland, weeping lovegrass is often dominant [27].
Weeping lovegrass is tolerant of partial shade, and in Beltsville, Maryland, weeping lovegrass established and grew in "almost" complete shade [27]. However, within 5 years of a fire near Globe, Arizona, increases in shrub live oak (Q. turbinella) appeared to reduce weeping lovegrass abundance. Basal cover of weeping lovegrass was inversely proportional to shrub live oak crown cover. In experiments where more than 50% of shrub live oak cover was removed, weeping lovegrass cover increased for up to 3 years [87]. Whether or not weeping lovegrass abundance was reduced by shrub live oak shading is unclear. It is possible that competition for root space or other interference was more important (see Belowground description).
In its nonnative US habitats, weeping lovegrass has been planted in many disturbed sites (see sections on Distribution and Occurrence and Introduction and spread). It persists on harsh sites and recovers rapidly following defoliation. In the desert grasslands of Sonita Valley, Arizona, cattle grazing seemed to encourage establishment and growth of weeping lovegrass and Lehmann lovegrass. Researchers tracked changes in lovegrass cover in an area where they were seeded; in an ungrazed, unseeded area; and in a grazed, unseeded area. Lovegrass cover generally increased over time in all areas, but over the 22-year study, increases were 2.5 times greater on grazed, unseeded areas than on ungrazed, unseeded areas even though the ungrazed, unseeded area was closest to the seeded area [10].
Reproduction of weeping lovegrass by vegetative means has only been described in one reference. Generally weeping lovegrass vegetative regeneration occurs only when stems are damaged or removed by grazing or fire. In a review, Crider [27] describes limited asexual reproduction by weeping lovegrass, but other sources have not. Crider reports that new stems may form at nodes on the stem rather than at the usual basal nodes. During warm wet weather, these new stems may root in the litter surrounding the crown and become detached from the parent plant [27]. Barkworth and others [8] noted that weeping lovegrass forms "innovations at the basal nodes" but that plants are not rhizomatous.
It is common for weeping lovegrass clumps to experience central stem death if ungrazed or unburned for 10 years or more. An accumulation of litter restricts tiller production at the center of undisturbed, mature plants [30], possibly because limited light within the interior of the tussock limits tiller recruitment [117]. During drought conditions, however, moisture is also important. Soil water content directly beneath clumps with open interiors was significantly (P<0.05) lower than that found at the tussock's periphery, which could promote outward tiller expansion. In a 10-year-old weeping lovegrass stand near Lubbock, Texas, tiller recruitment was stimulated by removing litter from the center of plants. Interior tiller recruitment was significantly greater (P<0.005) for plants with litter removed than for control plants. However, the results were opposite when litter removal was paired with defoliation. Interior tiller recruitment was significantly greater (P<0.001) for plants clipped to a 6-inch (15 cm) height with litter intact than for clipped plants with litter removed [117].
Eragrostis curvula is a species of grass known by the common name weeping lovegrass. Other common names include Boer lovegrass, curved lovegrass, Catalina lovegrass, and African lovegrass.
It is native to southern Africa. It is an introduced species on other continents.[1]
Eragrostis curvula is usually a long-lived perennial grass, but it is sometimes an annual plant. It is variable in appearance, and there are many different natural and cultivated forms.
In general, it forms tufts of stems up to 1.9 metres (6.2 ft) tall. The tufts may reach a diameter of 38 centimetres (1.25 ft).
The grass grows from a thick root network. Plants have been noted to have roots penetrating over 4 metres (13 ft) deep in the soil and 3 metres (9.8 ft) laterally. The roots can grow 5 centimetres (2.0 in) per day. The first root to grow into the soil from a seedling can send out up to 60 small rootlets per inch. The dense root system forms a sod.
The drooping leaves of the grass are up to 65 centimetres (2.13 ft) long but just a few millimeters wide, and they may have rolled edges. The inflorescence is a panicle with branches lined with centimeter-long spikelets. Each spikelet may contain up to 15 flowers. One panicle may produce 1000 seeds. Cultivated plants may produce two crops of seed per year. The plant self-fertilizes or undergoes apomixis, without fertilization.[1]
This grass is valuable as a forage for livestock in Africa, its native range.[2] There are many ecotypes. Several of these ecotypes were collected and introduced in the United States as cultivars. The grass was first planted in the United States in Stillwater, Oklahoma, in 1935. It was good for livestock, and its massive root network made it a good plant for erosion control.
It spread quickly as it was planted for ornamental purposes. It reached New York in the 1960s and in the 1970s and 80s it was planted alongside many highways such as the Long Island Expressway. Today it occurs as an invasive species in wild habitat from the southwestern United States to the East Coast. It can be found in woodlands, chaparral, prairie, grassland, and disturbed areas.[1] It is tolerant of very acidic and very basic soils; it grows easily in mine spoils. This species may hybridize with other Eragrostis, such as Eragrostis caesia, E. lehmanniana, and E. planiculmis.[3]
Cultivars of this grass include 'South African Robusta Blue', 'Witbank', 'Ermelo', 'Kromdraai', 'American Leafy', and 'Renner'.[4] Cultivars may be selected for yield, palatability for livestock, and drought resistance. It is planted along waterways in Sri Lanka and mountainsides in Japan, and it is used for oversowing fields in Argentina. In the United States it is often planted alongside Korean lespedeza.[5] It is planted as a nurse crop for sericea lespedeza, coastal panic grass, and switchgrass.[6]
It is an invasive species in some regions, such as parts of the United States and Victoria and other Australian states.[7] It is aggressive and can crowd out native plants. Its drought resistance helps it to survive in dry environments.[3][6]
In Lesotho, this grass is used to make baskets, brooms, hats, ropes, and candles, and it is used for food, as a charm, and in funeral rituals.[8]
Eragrostis curvula is a species of grass known by the common name weeping lovegrass. Other common names include Boer lovegrass, curved lovegrass, Catalina lovegrass, and African lovegrass.
It is native to southern Africa. It is an introduced species on other continents.
