Taxonomic name: Microstegium vimineum (Trin.) A. Camus
Synonyms: Andropogon vimineium, Eulalia viminea (Trin.) Kuntze, Eulalia viminea (Trin.) Kuntze var. imberbis (Nees ex Steud.) Kuntze , Eulalia viminea (Trin.) Kuntze var. variabilis Kuntze , Microstegium aristulatum Robyns & Tournay , Microstegium imberbe (Nees ex Steud.) Tzvelev, Microstegium vimineum var. imberbe, Microstegium willdenovianum Nees ex Lindl., Pollinia imberbis Nees var. genuina Hack. , Pollinia imberbis Nees var. willdenoviana (Nees) Hack. , Pollinia imberbis Nees ex Steud., Pollinia viminea (Trin.) Merr., Pollinia willdenoviana (Nees ex Lindl.) Benth.
Common names: annual jewgrass (English), Asian stilt grass (English), bamboo grass (English), Chinese packing grass
(English), flexible sesagrass (English), Japanese grass (English), Japanese stilt grass (English), Mary's grass (English), Nepal grass (English), Nepal microstegium (English), Nepalese browntop (English), Vietnamese stilt grass (English)
Organism type: grass
Microstegium vimineum is an annual grass native to Asia. It grows quickly, produces abundant seed and easily invades habitats that have been disturbed by natural and anthropogenic sources. Microstegium vimineum occupies riparian habitats, lawns, woodland thickets, damp fields and roadside ditches. It is usually found under moderate to dense shade in moist conditions, but it does not persist in areas with periodic standing water, or in full sunlight. The coldest winter temperature at which invasive populations occur is approximately -21° to -23° C. It occurs in soils of average potassium and phosphorus levels but high in nitrogen. Soil acidity, however, may limit nutrient availability. It spreads by rooting at nodes along the stem, and fruits and seeds disperse by water and on animals. Also, fruits have been transported on vehicles, and in hay and soil.
Microstegium vimineum is an annual grass which resembles a small bamboo plant. It can be recognised by its pale green lance shaped leaf with a distinctive silver midrib (Pennsylvania Field Guide, 2004). Young plants grow upright, but as the stem elongates, it becomes straggling and decumbent, with only the upper part of the stem upright and the lower part in contact with the ground, where the lower nodes root (Joan Ehrenfeld., pers.comm., 2005). Tu (2000) states that M. vimineum is a shade tolerant, annual grass (family Poaceae). It is usually 6-10dm in height, and the reclining stems can grow up to 1.0m long. In unfavourable conditions, the plant can be as little as 1-2 dm tall, and is capable of flowering in this condition (Joan Ehrenfeld., pers.comm., 2005). Tu (2000) further states that its culms (stems) are typically branched, rooting at the lower nodes, and the nodes and internodes are smooth and hairless. The lanceolate leaf blades are 5-8cm long, 2-15mm wide, sparsely pubescent on both surfaces, and distinctly tapered at both ends. The ligules are membranous, usually ciliate, and are 0.5-2.0mm long. The terminal or axillary inflorescence is a raceme, 2-7cm long, with an elongate peduncle and an angled disarticulating rachis. The hirsute fertile spikelets are deciduous, and occur in pairs, with one spikelet sessile and the other pedicellate. The glumes are equal in length (4.5-5.0mm) and awnless. The first glume is flat and 2-3 veined. The second glume is keeled and 3-veined. There are two lemmas per spikelet, with the lower one sterile and the upper, fertile one awnless or often with a slender awn 4-8mm. Both cleistogamous (flowers closed at pollination) and chasmogamous (flowers open) conditions have been reported for M. vimineum in Japan, with the axillary flowers all being cleistogamous. Cleistogamous panicles are contained in the upper 1-2 leaf sheaths, and remain appressed to the stem; these seeds are apparently dispersed as a unit in pieces of dead litter. The plant produces a very sparse, short fibrous root system (Joan Ehrenfeld., pers.comm., 2005). The fruit or caryopsis (grain) is yellowish to reddish, and ellipsoid (2.8-3.0mm) in shape. M. vimineum can be distinguished from other grasses by its thin, pale green, tapered leaf blades, and by its multiple spikelets that may be either terminal or arising from leaf axils. The alternate leaves have a silvery stripe of reflective hairs down the middle of the upper leaf surface. In the fall, identification becomes somewhat easier after the plant develops a slight purplish tinge (Tu, 2000).
Brachyelytrum erectum, Brachyelytrum septentrionale, Leersia virginica, Polygonum persicaria
agricultural areas, natural forests, riparian zones, ruderal/disturbed, urban areas, water courses, wetlands
Swearingen (1999) states that M. vimineum occurs on stream banks, river bluffs, floodplains, emergent and forested wetlands, moist woodlands, early successional fields, uplands, thickets, roadside ditches, gas and power line corridors and home lawns and gardens. It readily invades and is most common in disturbed, shaded areas like floodplains that are prone to natural scouring, and areas subject to mowing, tilling and other soil disturbing activities. It appears to be associated primarily with moist, acidic to neutral soils that are high in nitrogen. It occurs opportunistically in areas of open soil that are generally not already occupied by other species.
M. vimineum can also occur on upper forested slopes, particularly under disturbed canopy (including natural disturbances such as blowdowns); indeed, it often colonizes the bare soil of tree-throw mounds in otherwise uninvaded areas. It is also frequently found along hiking trails, despite dry and rocky conditions. A study of its distribution in several forested areas in New Jersey did not reveal a preference for any particular slope position, slope angle, or exposure direction (Kourtev et al. 1998), suggesting that it can occur on a very wide range of forested conditions.
Tu (2000) observes that most sites invaded by M. vimineum in the United States have acidic soils (pH 5.8 to 4.8), but some populations are on soils derived from limestone or marble with surficial soil that is neutral or only slightly acidic in reaction. He further states that the overall acidity of the soils, however, may limit nutrient availability. Soils are usually moist, and are often well-drained silty loams, sandy loams, or loams. Clay was not a significant component of the upper soil horizons in any of the soils invaded by M. vimineum (Hunt and Zaremba 1992, in Tu, 2000). No information was found regarding the optimal growing temperatures or the temperature limits of this species. The coldest winter temperature at which invasive populations of M. vimineum occur is approximately -21° to -23° C (Redman, 1995, in Tu, 2002). It can grow and produce seeds with as little as 5% full sunlight, but maximum growth and seed production occurs at 25-50% full sunlight (Winter et al.1982, Horton and Neufeld, 1998, in Tu, 2000).
Tu (2000) reports that Microstegium vimineum is capable of invading wildland areas and swiftly replacing natural communities with nearly monospecific stands. It is generally slow to invade undisturbed areas but rapidly fills disturbed areas such as flood-scoured streamsides and sewer line rights-of-way that are mowed once a year. Once established, M. vimineum is able to crowd out native herbaceous vegetation in wetlands and forests within three to five years (Hunt, 1992; Barden, 1987, in Tu, 2000). Additionally, M. vimineum may be responsible for altering natural soil conditions, creating an inhospitable environment for many native species. In areas that have been invaded by M. vimineum, both litter and organic soil horizons were thinner than in uninvaded areas, and that the pH of soils in invaded sites was significantly higher than in uninvaded sites (Kourtev et al. 1998, in Tu, 2000). There is no indication that M. vimineum produces allelopathic chemicals (Woods, 1989, in Tu, 2000).
Established populations of M. vimineum usurp quality nesting habitat from quail and other wildlife. In addition, it creates excellent habitat for rats, especially cotton rats (Sigmodon spp.), which often prey on the nests of native bobwhite quail (Colinus virginianus) and attract other predators as well (A. Houston, pers. comm., in Tu, 2000).
M. vimineum also appears able to change soil functions by raising pH and immobilising N (Ehrenfeld et al. 2001). Kourtev et al. 1999 found that M. vimineum populations were associated with higher densities of exotic (European) earthworms than nearby uninvaded soils
Tu (2000) cites that in the early 1900s, M. vimineum was used extensively as a packing material for porcelain, especially fine China porcelain, which may have contributed to its invasion into the United States. Culms of this grass have also been used for basket weaving. It has not been documented as being intentionally planted as an ornamental, for erosion control, or for forage.
VANHP (Undated) states that it was formerly known as Eulalia vimineum.
Tu (2000) states that Microstegium vimineum was introduced to North America from Asia, where it is native to India, Nepal, China, Japan, Malaysia (Swearingen, 1999) and Korea (Swearingen, 1999). It was first identified in the United States in 1919 in Tennessee, and by 1960 had spread (probably by hay and soil) to Ohio, Pennsylvania, and most Atlantic coastal states. Reported occurrences of M. vimineum in North America currently include 24 states (USDA-NRCS, 2002). IPANE (2004) reports 3 occurances of M. vimineum in Massachusetts, suggesting spread further into New England. Corrigan (Undated) states that it has also been reported from Puerto Rico.
Introduction pathways to new locations
Floating vegetation/debris: Floating vegetation/debris - litter and seeds are undoubtedly moved in floodwaters, including overland flow on slopes (not necessarily from a stream) (Joan Ehrenfeld., pers.comm., 2005).
Other: Also, the species may be spread by animals in adhering mud or on fur; though there is not much information, it is apparent the species moves to new locations independent of people's activities (Joan Ehrenfeld., pers.comm., 2005).
People sharing resources: Swearingen (1999) states that M. vimineum was introduced into Tennessee around 1919; it may have accidentally escaped as a result of its use as a packing material for porcelain in China.
Local dispersal methods
Agriculture (local): "Swearingen (1999) states that the seeds are transported widely in hay and soil."
Natural dispersal (local): Swearingen (1999) states that it is a clonal species that spreads by rooting at nodes along the stem. New culms emerge from each node.
On animals: Tu (2000) states that though M. vimineum does not exhibit any special adaptations for seed/fruit dispersal, such as hooks or barbs, its seeds are small and often adhere to animal fur or clothing.
On clothing/footwear: Tu (2000) states that though M. vimineum does not exhibit any special adaptations for seed/fruit dispersal, such as hooks or barbs, its seeds are small and often adhere to animal fur or clothing.
Other (local): Gravity - surface flow of water during storms (overland flow not associated with stream flooding) (Joan Ehrenfeld., pers.comm., 2005).
Road vehicles: "The fruits have been observed being transported on automobiles (Mehrhoff 2000, in Tu, 2000).
Water currents: The floating fruits of M. vimineum can disperse throughout an entire wetland or alluvial floodplain during high-water events (Woods 1989, Mehrhoff 2000, in Tu, 2000).
Tu (2000) states that manual and mechanical, environmental/cultural, and chemical methods are all useful to varying degrees in controlling M. vimineum.
For more details please see management information.
Soils on which Microstegium vimineum occur are typically average in levels of potassium and phosphorus and high in nitrogen (Redman, 1995, in Tu, 2000). Kourtev et al. 1998 found that the species is associated with high nitrate concentrations and less acidic conditions than uninvaded soils. Also, Kourtev et al. 1999 showed that M. vimineum has high levels of nitrate reductase in its leaves, suggesting a preferential uptake of nitratas a N source.
Derr and Tech (2004) state that Japanese stiltgrass has a fibrous root system. Seeds gereminate in late spring, and plants reach flowering status in mid-autumn. Swearingen (1999) states that M. vimineum is a clonal species that spreads by rooting at nodes along the stem. New culms emerge from each node. Each plant can produce an estimated 100 to 1,000 seeds. Once established at a site, seed stored in the soil will ensure regrowth for several to many years.
Tu (2000) states that M. vimineum relies entirely on its seed bank for its annual recruitment. Seeds may need a period of stratification (cool temperatures and high moisture) before they will germinate (Woods, 1989, in Tu, 2000). Seeds stored in the soil may remain viable as long as five years (Barden 1991, in Tu, 2000). Seeds may have low germination rates (Woods, 1989, in Tu, 2000), but each plant produces many seeds. Seeds are also able to survive submersion in water for periods of up to 10 weeks. Seeds can germinate while under water, but the plants do not grow (Barden, 1991, in Tu, 2000). If standing water is removed, more seeds will germinate shortly afterwards.
Reviewed by: Joan G. Ehrenfeld, Ph. D. Professor Dept. Ecology, Evolution, and Natural Resources, Cook College, Rutgers University New Brunswick USA
Compiled by: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG)
Last Modified: Wednesday, 13 April 2005