Themeda quadrivalvis
(grader grass)

Pictures

Picture	Title	Caption	Copyright
Title Habit Caption Themeda quadrivalvis (grader grass); roadside habit. Australia. July 2011. Copyright ©Harry Rose (Macleay Grass Man)/via wikipedia - CC BY 2.0	Habit	Themeda quadrivalvis (grader grass); roadside habit. Australia. July 2011.	©Harry Rose (Macleay Grass Man)/via wikipedia - CC BY 2.0
Title Flowerhead Caption Themeda quadrivalvis (grader grass); flowerhead. Australia. July 2011. Copyright ©Harry Rose (Macleay Grass Man)/via wikipedia - CC BY 2.0	Flowerhead	Themeda quadrivalvis (grader grass); flowerhead. Australia. July 2011.	©Harry Rose (Macleay Grass Man)/via wikipedia - CC BY 2.0

Identity

Preferred Scientific Name

• Themeda quadrivalvis (L.) Kuntze

Preferred Common Name

• grader grass

Other Scientific Names

• Andropogon ciliatus (L.f.) Thunb.
• Andropogon quadrivalvis L.
• Anthistiria barbata Desf.
• Anthistiria scandens Roxb.
• Themeda chinensis (A.Camus) S.L.Chen & T.D.Zhuang
• Themeda ciliata (L.f.) Hack.
• Themeda dacruzii Birari
• Themeda echinata A.Camus ex Keng
• Themeda yuanmounensis S.L.Chen & T.D.Zhuang

International Common Names

• English: habana grass; habana oatgrass; kangaroo grass
• French: herbe de bondé; herbe de javel; herbe kangourou; herbe Saint-Paul
• Chinese: zhong hua jian

Local Common Names

• Cuba: yerba americana
• Dominican Republic: arrocillo; yerba francesa
• Haiti: herbe Dame Michel; herbe Madame Michel
• Lesser Antilles: Christmas grass

EPPO code

• THMQU (Themeda quadrivalvis)

Summary of Invasiveness

Themeda quadrivalvis is an annual grass found as a weed in grasslands, disturbed areas and agricultural land. It is native to the Indian Subcontinent and South East Asia but has been widely introduced to the Americas, Africa and Oceania. It is recorded as invasive in Mexico, Cuba, Dominican Republic, Reunion, Australia, Fiji and New Caledonia. It is spread unintentionally as a contaminant in straw packing, pasture seed and on vehicles and machinery. Once established, it forms dense thickets that prevent seedling establishment; this causes ecosystem change, altered fire regimes and reduced native biodiversity.

Taxonomic Tree

• Domain: Eukaryota
•     Kingdom: Plantae
•         Phylum: Spermatophyta
•             Subphylum: Angiospermae
•                 Class: Monocotyledonae
•                     Order: Cyperales
•                         Family: Poaceae
•                             Genus: Themeda
•                                 Species: Themeda quadrivalvis

Notes on Taxonomy and Nomenclature

The family Poaceae comprises 707 genera and 11,337 species distributed worldwide (Stevens, 2012). The genus Themeda comprises 18-27 species, all of which are native to tropical and subtropical regions of the Eastern Hemisphere, primarily South East Asia (Barkworth et al., 2007). Themeda species are drought tolerant and exhibit considerable ecological and morphological diversity. Within this genus, two sections are recognized based on the characters of the raceme: section Primothemedae with homogamous spikelet pairs arranged at different levels and section Themeda with homogamous spikelet pairs arranged at the same level in the raceme base (Zhang et al., 2014).

Description

Description from Flora of China Editorial Committee (2017):

Culms moderately robust, erect or geniculate at base, 1 m tall. Leaf sheaths glabrous or with tubercle-based bristles at mouth; leaf blades flat or folded, up to 30 x 0.3-0.9 cm, glabrous, abruptly acute to acuminate; ligule 3 mm. Compound panicle large, dense; spathes and spatheoles lanceolate-caudate, glabrous, innermost 1.3-1.7 cm. Raceme composed of a triad of 1 sessile and 2 pedicelled spikelets above the involucre of 2 homogamous pairs. Homogamous spikelets all sessile, arising at same level, barren, both glumes present, 4.5-6 mm, lanceolate, stiffly setose in upper half with 3-4 mm, tubercle-based bristles. Sessile spikelet 4-4.5 mm; callus 0.8-1 mm, subacute, brown bearded; lower glume dorsally rounded, dark brown at maturity, pubescent, often thinly or glabrous on lower back; awn 3.5-4 cm. Pedicelled spikelet 4-6 mm, barren.

Plant Type

Distribution

T. quadrivalvis is native to the Indian subcontinent (India and Nepal) and Bangladesh, Myanmar and Thailand in South East Asia. It has been widely introduced and is now naturalized in the USA, Central America, the Caribbean, South America, Africa, Asia, Australia and several islands in Oceania (Zuloaga et al., 2003; Broome et al., 2007; Zuloaga et al., 2008; Acevedo-Rodríguez and Strong, 2012; Sánchez-Ken et al., 2013; Agriculture Victoria, 2017; Clayton et al., 2017; FAO, 2017; PIER, 2017; USDA-ARS, 2017; USDA-NRCS, 2017). It is recorded as invasive in Mexico, Cuba, Dominican Republic, Reunion, Australia, Fiji and New Caledonia (Mir, 2012; Oviedo Prieto et al., 2012; Espinosa-García and Villaseñor, 2017; PIER, 2017; Weeds of Australia, 2017).

Distribution Table

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

History of Introduction and Spread

T. quadrivalvis was accidentally introduced to Australia in the 1930s as a contaminant in supplies of straw packing and since then it has spread as a contaminant in pasture seed. By the 1960s it was reported in Queensland (ca 1963) and soon after in the Northern Territory (ca 1967-1968). It is now well established in the Katherine and Darwin regions and continues to spread. It is also spreading rapidly along the east coast of Queensland, and into drier inland areas. It is now a major weed, especially in central coastal and northern Queensland where infestations continue to expand (Parsons and Cuthbertson, 2001; Keir and Vogler, 2006; Agriculture Victoria, 2017; Weeds of Australia, 2017).

In the USA, T. quadrivalvis has been reported as naturalized since 1945 and occurs in California, Kansas, Louisiana and Florida (USDA-NRCS, 2017). In Kansas, this species was introduced as a contaminant in seed sold for bird feeders (Towne and Barnard, 2000).

In Mexico, T. quadrivalvis was first collected in 1884 in Sonora, but this collection was fortuitous and the species was probably not established in Sonora. It was not reported again until 2006 when it was collected in a pasture along a highway in Morelos. By 2012, large populations of T. quadrivalvis were identified across the state of Morelos where it continues to spread (Sánchez-Ken et al., 2013).

In the Caribbean, T. quadrivalvis appears in herbarium collections made in 1880 in Martinique, 1905 in Barbados, 1915 in Hispaniola and 1935 in Guadaloupe (US National Herbarium, 2017).

Introductions

Risk of Introduction

The risk of introduction of T. quadrivalvis is moderate as this species is not actively commercialized or promoted for agricultural or horticultural purposes. However, it has been repeatedly introduced accidentally as a seed contaminant.

Habitat

T. quadrivalvis grows in grasslands, coastal thickets, grassy woodlands, riverine areas, dry slopes, wastelands, roadsides and disturbed areas (Agriculture Victoria, 2017; Flora of China Editorial Committee, 2017; Weeds of Australia, 2017). It also grows as a weed on agricultural land (FAO, 2017).

Habitat List

Hosts/Species Affected

T. quadrivalvis has become an aggressive weed in sugarcane fields, citrus orchards and pastures and also in lucerne and other legume seed crops (Smith, 2002; FAO, 2017; Weeds of Australia, 2017).

Host Plants and Other Plants Affected

Growth Stages

Biology and Ecology

Genetics

The chromosome number reported for T. quadrivalvis is 2n = 40 (Barari, 1980; FAO, 2017).

Physiology and Phenology

T. quadrivalvis is an annual grass, though in tropical areas it may grow as a short-lived perennial (Zuloaga et al., 2003; Barkworth et al., 2007; FAO, 2017; Flora of China Editorial Committee, 2017). Growth is rapid under favourable conditions and plants may reach a height of 2 m within 6-8 weeks (Parsons and Cuthbertson, 2001). Flowering begins 5 to 6 weeks after germination and ripe seeds are present at 10 weeks (Bishop 1981). In India, T. quadrivalvis flowers from October to January (FAO, 2017). In Australia, flowers generally appear between February and June (summer/autumn), but can also occur during winter (Keir and Vogler, 2006; Weeds of Australia, 2017). In China, it flowers and fruits from June to December (Flora of China Editorial Committee, 2017). It is a prolific seeder, producing ca 633,000 seeds/kg (Agriculture Victoria, 2017). Seed may remain viable for at least five years (Bishop 1981; Parsons and Cuthbertson 2001; Smith 2002).

Environmental Requirements

T. quadrivalvis is able to grow in a wide range of moisture regimens at low to medium elevations. It prefers areas receiving between 500 and 1250 mm of rainfall annually, but it can persist in areas receiving as little as 375 mm or more than 3500 mm (Keir and Vogle, 2006; Agriculture Victoria, 2017). It is also adapted to a wide range of soil types including sandy loam soil, clay loams, and lateritic soils with pH in the range 7.0-8.5. Burning encourages seed germination (FAO, 2017).

Climate

Latitude/Altitude Ranges

Air Temperature

Rainfall

Rainfall Regime

Soil Tolerances

Soil drainage

• free

Soil reaction

• alkaline
• neutral

Soil texture

• heavy
• light
• medium

Means of Movement and Dispersal

T. quadrivalvis spreads by seed. Seeds are transported over long distances by both humans and animals as they adhere to fur or clothing. They are also a contaminant in pasture seed and hay and can also be spread in soil or mud moved by road graders or carried by other vehicles and machinery (Parsons and Cuthbertson, 2001; Smith, 2002; Keir and Vogler, 2006; FAO, 2017; Weeds of Australia, 2017).

Pathway Causes

Pathway Vectors

Environmental Impact

T. quadrivalvis can significantly reduce the biodiversity of native grasslands, savannas, woodlands, coastal forests and rangelands, particularly in areas that are overgrazed or disturbed. It is a fast-growing grass that replaces native plants and forms tall, dense thickets that can cover large tracts of land. These dense thickets exclude almost all other species by preventing seedling establishment. It also alters the fire regime due to its greater biomass than the native plants it replaces, and hence its higher fuel load. Fires in invaded areas cause a thinning of the native woodlands and a reduction in the number of trees in the ecosystem, resulting in a change from native savannas and woodlands to areas dominated by exotic grasses (Parsons and Cuthbertson, 2001; Smith, 2002; Keir and Vogler, 2006; FAO, 2017; Weeds of Australia, 2017).

Impact: Biodiversity

In Australia, a study showed that T. quadrivalvis can significantly reduce the richness and abundance of reptiles in invaded areas by decreasing habitat heterogeneity and structural habitat complexity required to maintain populations of native reptiles (Abom et al., 2015).

Social Impact

T. quadrivalvis is also a very common weed along roadsides, where it can quickly become a safety hazard by reducing visibility for drivers (Weeds of Australia, 2017).

Risk and Impact Factors

• Proved invasive outside its native range
• Has a broad native range
• Abundant in its native range
• Highly adaptable to different environments
• Is a habitat generalist
• Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
• Pioneering in disturbed areas
• Highly mobile locally
• Fast growing
• Has high reproductive potential
• Gregarious
• Has propagules that can remain viable for more than one year

• Ecosystem change/ habitat alteration
• Increases vulnerability to invasions
• Modification of fire regime
• Modification of successional patterns
• Monoculture formation
• Negatively impacts agriculture
• Reduced amenity values
• Reduced native biodiversity
• Threat to/ loss of native species

• Competition - monopolizing resources
• Competition - smothering
• Rapid growth

• Highly likely to be transported internationally accidentally
• Difficult to identify/detect as a commodity contaminant
• Difficult to identify/detect in the field
• Difficult/costly to control

Uses

In India, T. quadrivalvis is used to produce fodder for livestock and for thatching (Keir and Vogler, 2006; FAO, 2017).

Uses List

Animal feed, fodder, forage

• Fodder/animal feed
• Forage

Similarities to Other Species/Conditions

T. quadrivalvis appears similar to other Themeda species such as: T. triandra, T. avenacea and T. arguens. These species can be distinguished by the following morphological and ecological traits (Descriptions from Weeds of Australia, 2017):

• T. quadrivalvis is a moderately-sized to relatively large short-lived (annual) grass growing up to 1.8 m tall. Its individual flower spikelets are relatively small (4-7 mm long), stiffly hairy (i.e. setose) in the upper half, and its seeds are topped with a relatively fine awn (10-45 mm long).
• T. triandra is a moderately-sized long-lived (perennial) grass usually growing less than 1 m tall. Its individual flower spikelets are moderately-sized (6-14 mm long), hairless (i.e. glabrous) or slightly hairy (i.e. hispid), and its seeds are topped with a relatively large awn (25-70 mm long).
• T. avenacea is a large long-lived (perennial) grass often growing up to 2 m tall. Its individual flower spikelets are very large (13-30 mm long), densely hairy (i.e. villous), and its seeds are topped with a large and robust awn (40-100 mm long).
• T. arguens is a large short-lived (annual) grass growing up to 3 m tall. Its individual flower spikelets are moderately-sized (6-11 mm long), softly hairy (i.e. pubescent), and topped with a large and robust awn (50-90 mm long).

Prevention and Control

Cultural Control and Sanitary Measures

Preventing the introduction of T. quadrivalvis seeds to new sites is the first step in controlling its spread. Since the seeds of this species are not easily dispersed by natural means, good sanitary practices such as washing down vehicles and machinery and ensuring hay, pasture seed and stock are uncontaminated, will help prevent its spread (Parsons and Cuthbertson 2001; Keir and Vogler, 2006; Weeds of Australia, 2017).

Physical/Mechanical Control

Small infestations can be controlled manually, preferably before seeding. Because T. quadrivalvis is an annual plant, measures should be directed primarily to prevent the formation of new seeds. Mechanical methods include hand-pulling and cutting plants before or during flowering (Parsons and Cuthbertson 2001; Keir and Vogler, 2006; Weeds of Australia, 2017).

Chemical Control

In Australia, chemical herbicides recommended for the control of T. quadrivalvis include glyphosate, paraquat, 2,2-DPA and TCA (Parsons and Cuthbertson 2001; Keir and Vogler, 2006; Weeds of Australia, 2017).

References

Abom, R., Vogler, W., Schwarzkopf, L., 2015. Mechanisms of the impact of a weed (grader grass, Themeda quadrivalvis) on reptile assemblage structure in a tropical savannah. Biological Conservation, 191, 75-82. http://www.sciencedirect.com/science/article/pii/S0006320715002396 doi: 10.1016/j.biocon.2015.06.016

Acevedo-Rodríguez P, Strong MT, 2012. Catalogue of the Seed Plants of the West Indies. Smithsonian Contributions to Botany. 98. Washington DC, USA: Smithsonian Institution.1192 pp. http://botany.si.edu/Antilles/WestIndies/catalog.htm

Agriculture Victoria, 2017. Victorian Resources Online. http://vro.agriculture.vic.gov.au

Barkworth ME, Anderton LK, Capels KM, Long S, Piep MB, 2007. Manual of grasses for North America, Utah, USA: Utah State University Press.627 pp.

Birari SP, 1980. Apomixis and sexuality in Themeda Forssk. at different ploidy levels (Gramineae). Genetica, 54, 133-139.

Bishop HG, 1981. Grader grass: a nuisance weed. Queensland Agricultural Journal, 107, 235-239.

Broome R, Sabir K, Carrington S, 2007. Plants of the Eastern Caribbean. Barbados: University of the West Indies.http://ecflora.cavehill.uwi.edu/index.html

Clayton WD, Govaerts R, Harman KT, Williamson H, Vorontsova M, 2016. World Checklist of Poaceae. Kew, UK: Royal Botanic Gardens, Kew.http://apps.kew.org/wcsp/

Espinosa-García FJ, Villaseñor JL, 2017. Biodiversity, distribution, ecology and management of non-native weeds in Mexico: a review. Revista Mexicana de Biodiversidad, 88(1), 76-96.

FAO, 2017. Ecocrop. http://ecocrop.fao.org/ecocrop/srv/en/home

Flora do Brasil, 2017. Brazilian Flora. http://floradobrasil.jbrj.gov.br/

Flora of China Editorial Committee, 2017. Flora of China. St. Louis, Missouri and Cambridge, Massachusetts, USA: Missouri Botanical Garden and Harvard University Herbaria.http://www.efloras.org/flora_page.aspx?flora_id=2

Keir AF, Vogler WD, 2006. A review of current knowledge of the weedy species Themeda quadrivalvis (grader grass). Tropical Grasslands, 40, 193-201.

Mir C, 2012. Estrategia Nacional de Especies Exóticas Invasoras Realizado en el marco del Proyecto “Mitigando las amenazas de las especies exóticas invasoras en el Caribe Insular”. Santo Domingo, Dominican Republic: Ministerio de Medio Ambiente y Recursos Naturales.

Oviedo Prieto R, Herrera Oliver P, Caluff MG, et al., 2012. National list of invasive and potentially invasive plants in the Republic of Cuba - 2011. (Lista nacional de especies de plantas invasoras y potencialmente invasoras en la República de Cuba - 2011). In: Bissea: Boletín sobre Conservación de Plantas del Jardín Botánico Nacional de Cuba , 6(Special Issue 1) . 22-96.

Parsons, W. T., Cuthbertson, E. G., 2001. Noxious weeds of Australia, (Ed.2) . Collingwood, Australia: CSIRO Publishing.xii + 698 pp.

PIER, 2017. Pacific Islands Ecosystems at Risk. Honolulu, USA: HEAR, University of Hawaii.http://www.hear.org/pier/index.html

Sánchez-Ken JG, Cerros-Tlatilpa R, Vibrans H, 2013. Themeda quadrivalvis (Sacchareae, Panicoideae, Poaceae), una maleza reglamentada presente y establecida en el estado de Morelos, México. Botanical Sciences, 91(4), 531-536.

Smith NM, 2002. Weeds of the wet/dry tropics of Australia - a field guide. Darwin, Australia: Environment Centre NT.112 pp.

Stevens PF, 2012. Angiosperm Phylogeny Website. http://www.mobot.org/MOBOT/research/APweb/

Towne EG, Barnard I, 2000. Themeda quadrivalvis (Poaceae: Andropogoneae) in Kansas: An exotic plant introduced from birdseed. SIDA, Contributions to Botany, 19, 201-203.

USDA-ARS, 2017. Germplasm Resources Information Network (GRIN). Online Database. Beltsville, USA: National Germplasm Resources Laboratory.http://www.ars-grin.gov/cgi-bin/npgs/html/tax_search.pl

USDA-NRCS, 2016. The PLANTS Database. Baton Rouge, USA: National Plant Data Center.https://collections.nmnh.si.edu/search/botany/

Weeds of Australia, 2017. Weeds of Australia – Biosecurity Queensland Edition. Queensland Government.https://keyserver.lucidcentral.org/weeds/data/media/Html/search.html?zoom_query=

Zhang Y, Hu X, Liu Y, Liu Q, 2014. Caryopsis micromorphological survey of the genus Themeda (Poaceae) and allied spathaceous genera in the Andropogoneae. Turkish Journal of Botany, 38(4), 665-676.

Zuloaga FO, Morrone O, Davidse G, Filgueiras TS, Peterson PM, Soreng RJ, Judziewicz EJ, 2003. Catalogue of New World grasses (Poaceae): III. Subfamilies Panicoideae, Aristidoideae, Arundinoideae, and Danthonioideae. Contributions from the United States National Herbarium, 46, 7-662.

Contributors

16/08/18 Original text by:

Julissa Rojas-Sandoval, Department of Botany-Smithsonian NMNH, Washington DC, USA

Distribution Maps