Digitaria fuscescens
(yellow crab grass)

Pictures

Picture	Title	Caption	Copyright
Title Habit Caption Digitaria fuscescens (yellow crab grass); habit and typical habitat. Copyright ©Cyrille Mas/via http://tropical.theferns.info/ - CC BY-NC-ND 3.0	Habit	Digitaria fuscescens (yellow crab grass); habit and typical habitat.	©Cyrille Mas/via http://tropical.theferns.info/ - CC BY-NC-ND 3.0
Title Habit Caption Digitaria fuscescens (yellow crab grass); close-up of structure and habit. Copyright ©Cyrille Mas/via http://tropical.theferns.info/ - CC BY-NC-ND 3.0	Habit	Digitaria fuscescens (yellow crab grass); close-up of structure and habit.	©Cyrille Mas/via http://tropical.theferns.info/ - CC BY-NC-ND 3.0
Title Inflorescence Caption Digitaria fuscescens (yellow crab grass); inflorescence. Copyright ©Cyrille Mas/via http://tropical.theferns.info/ - CC BY-NC-ND 3.0	Inflorescence	Digitaria fuscescens (yellow crab grass); inflorescence.	©Cyrille Mas/via http://tropical.theferns.info/ - CC BY-NC-ND 3.0
Title Seeds Caption Digitaria fuscescens (yellow crab grass); seeds. Copyright Public Domain - Released by Jose Hernandez, hosted by the USDA-NRCS PLANTS Database.	Seeds	Digitaria fuscescens (yellow crab grass); seeds.	Public Domain - Released by Jose Hernandez, hosted by the USDA-NRCS PLANTS Database.

Identity

Preferred Scientific Name

• Digitaria fuscescens (J.Presl) Henrard

Preferred Common Name

• yellow crab grass

Other Scientific Names

• Digitaria fuscescens (J.Presl) J.W.Moore
• Digitaria pseudoischaemum Buse
• Panicum fuscescens J.Presl
• Panicum pseudo-ischaemum (Buse) Boerl.
• Paspalum fuscescens J.Presl
• Paspalum micranthum Desv.
• Syntherisma fuscescens (J.Presl) Scribn.

International Common Names

• English: creeping crabgrass; Y grass
• Portuguese: capim-de-roca; capim-de-vaca

Local Common Names

• Brazil: cuspo-do-taquarizano; grama-mata-éagua
• Indonesia: kakawatan; rumput tembagan
• USA/Hawaii: creeping kukaepua’a

Summary of Invasiveness

D. fuscescens is an annual, to perennial grass that is a weed of cultivated crops and disturbed soils (Useful Tropical Plants, 2016). It is also a weed of turf grass (Uddin et al., 2012). The species is listed as invasive in Asia (Chagos Archipelago), South America (Colombia, Peru) and Oceania (Fiji, French Polynesia, USA-Hawaii) (PIER, 2016).

Taxonomic Tree

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

Notes on Taxonomy and Nomenclature

Digitaria is a genus in the Poaceae with about 220 species that are distributed in the tropical, subtropical and temperate regions of the world (Vega and Rugólo de Agrasar, 2007). The common name crabgrass is applied to many species in the genus. Digitaria comes from Digitus, the Latin word for "finger", referring to the long, finger-like inflorescences produced by the grasses. From the names applied to the species, D. fuscescens (J.Presl) J.W.Moore is an illegitimate name (Quattrocchi, 2006). The specific name fuscescens is New Latin for "blackish", from Latin fuscus, "dark".

Description

The following description is from PROTA (2016):

Annual, ascending from a creeping base; culms 4–30 cm. high. Leaf-blades 1–5 cm. long, 1–4 mm. wide. Inflorescence of 2–4 (typically 2) digitate racemes; racemes 1–7 cm. long, the spikelets ternate on a ribbon-like winged rachis with low rounded midrib. Spikelets narrowly ovate-elliptic, 1.2–1.6 mm. long; lower glume a minute hyaline rim or absent; upper glume as long as the spikelet, 5-nerved (rarely 3-nerved), glabrous; lower lemma as long as the spikelet, 7-nerved, glabrous; fruit ellipsoid, pallid to light brown.

Plant Type

Distribution

D. fuscescens is mainly present in tropical and subtropical regions (USDA-ARS, 2016). The species is native to India, tropical Asia and Indonesia (PIER, 2016; PROSEA, 2016). In USDA-ARS (2016) it is also listed as native to Bolivia. It is found in Central America, the Caribbean, South America, Africa, Asia and Oceania (See Distribution Table for details).

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

Information about the introduction of the species to areas outside its native range and/or its spread is not readily available. Outside its native range, the earliest collections are from the late 1800’s from Hawaii and by the early 1900’s from Brazil (Bernice Pauahi Bishop Museum, 2016; Missouri Botanical Garden, 2016). It is reported from Fiji by 1919, misidentified as D. longiflora (Gardner, 2007). Being a weed at crop sites, it is possible that the species has been dispersed unintentionally as a contaminant in agricultural products, through soil or transported by humans (PIER, 2016; PROTA, 2016). Another possible reason for its introduction is to be used for erosion control (PROSEA, 2016).

Introductions

Risk of Introduction

There is almost no information available about the introduction, dispersion and biology of the species to properly assess the risk of introduction. It is reported as cultivated outside its native range and used for erosion control (Vega and Rugólo de Agrasar, 2007; PROSEA, 2016; PROTA, 2016). It is also a weed of cultivated fields (PIER, 2016). Although no information is available about the effects on other species or the habitats where it is naturalised, based on its capability of growing in different habitats and spreading vegetatively, D. fuscescens has a medium risk of introduction into tropical areas.

Habitat

D. fuscescens is a grass species found at beaches, sand dunes, periodically burned grassy savanna, periodically flooding grasslands, forest borders, waste places, field borders, roadsides, hillsides, along trails and in cultivated areas (Rebellato and Nunes da Cunha, 2005; Quattrocchi, 2006; PIER, 2016; PROSEA, 2016; PROTA, 2016). It is found from sea level to about 1350 m elevation (PROSEA, 2016; Missouri Botanical Garden, 2016).

Habitat List

Hosts/Species Affected

The species is reported as a weed of crops, including rice fields in Indonesia and Laos (Kosaka et al., 2006; PIER, 2016; PROTA, 2016).

Biology and Ecology

Genetics

The chromosome number reported for D. fuscescens is n=9 (Dujardin, 1979). Accessions of the species are stored in the National Plant Germplasm System (USDA-ARS, 2016).

Reproductive Biology

D. fuscescens reproduces by seeds and vegetatively through creeping stolons (PROSEA, 2016; Useful Tropical Plants, 2016). It is wind pollinated (Useful Tropical Plants, 2016).

Longevity
D. fuscescens is reported as both an annual and a perennial (Uddin et al., 2010; PROTA, 2016).

Associations

D. fuscescens grows in Venezuela on savannas with species of Trachypogon, Curatella, Byrsonima and Bowdichia (Vega and Rugolo de Agrasar, 2005).

Environmental Requirements

Almost no information is available on the environmental requirements of this species. Rebellato and Nunes da Cunha (2005) consider D. fuscescens as a humidity indicator species, appearing only during the rainy months on a flooding grassland in Matto Grosso do Sul, Brazil. It is reported by Uddin et al. (2010) as growing on sand, sandy clay loam, clay and coarse sandy clay; in temperatures of 24-32°C; and with an annual rainfall of 1800 to 2000 mm. The species grows in full sun (Vega and Rugólo de Agrasar, 2002).

Climate

Latitude/Altitude Ranges

Air Temperature

Rainfall

Rainfall Regime

Soil Tolerances

Soil drainage

• free
• seasonally waterlogged

Soil texture

• heavy
• light
• medium

Means of Movement and Dispersal

D. fuscescens is dispersed by water and by stolon fragments (PIER, 2016). It may have been deliberately introduced to some areas for erosion control (PROSEA, 2016).

Pathway Causes

Pathway Vectors

Impact Summary

Risk and Impact Factors

• Proved invasive outside its native range
• Has a broad 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
• Long lived
• Fast growing
• Has high reproductive potential
• Gregarious
• Has propagules that can remain viable for more than one year
• Reproduces asexually

• Monoculture formation
• Negatively impacts agriculture

• Competition - monopolizing resources
• Rapid growth

• Highly likely to be transported internationally accidentally
• Difficult to identify/detect as a commodity contaminant

Uses

D. fuscescens is recommended for erosion control in exposed slopes (PROSEA, 2016).

Uses List

Environmental

• Erosion control or dune stabilization

Similarities to Other Species/Conditions

D. fuscescens can be confused with D. longiflora. The spikelets of D. longifolia are conspicuously pilose and the plants are densely cespitose, while in D. fuscescens the spikelets are glabrous to glabrescent and the plants are stoloniferous (Giraldo-Cañas, 2005).

Prevention and Control

Cultural Control

According to Uddin et al. (2012), D. fuscescens can be controlled in turf grass by a combination of mowing, watering and fertilization; complemented with chemical control. Mowing height should not be low as it will promote weeds in the turf grass. Application of fertilizer at intervals throughout the growing period is recommended and not during dormant or low growth periods as this may encourage weed growth.

Physical/Mechanical Control

Hand pulling and hoeing is recommended for small areas (Uddin et al., 2012).

Chemical control

D. fuscescens can be controlled with a mix of MSMA (monosodium methyl arsenate), dalapon and 2, 4-D (Anon, 1968).

Gaps in Knowledge/Research Needs

Information about the biology of this species, the environmental requirements and the impacts on habitats or other species is needed for a complete assessment of the invasiveness of the species.

References

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

Anon, 1968. General non-selective weed control with monosodium acid methane arsenate (MSMA) based mixtures in rubber plantations., Rubber Research Institute Malaya Plant Bulletin, 95:52-55

Bernice Pauahi Bishop Museum, 2016. Bernice Pauahi Bishop Museum Database. http://www.bishopmuseum.org/collections-3/botany/

Dujardin M, 1979. IOPB chromosome number reports LXIII. , Taxon, 28:275-276

Flora do Brasil, 2016. Brazilian Flora 2020 in construction. http://reflora.jbrj.gov.br/reflora/listaBrasil/ConsultaPublicaUC/ConsultaPublicaUC.do#CondicaoTaxonCP

Gardner R, 2007. Grasses (Gramineae) of the central Pacific Ocean region, Records of the Auckland Museum, 44:43-83

Giraldo-Cañas D, 2005. Las especies colombianas del género Digitaria (Poaceae: Panicoideae:Paniceae)., Caldasia, 27(1):25-87

Giraldo-Cañas D, 2011. Catálogo de la familia Poaceae en Colombia., Darwiniana, 49(2):139-247

Kosaka Y, Takeda S, Sithirajvongsa S, Xaydala K, 2006. Plant diversity in paddy fields in relation to agricultural practices in Savannkhet province, Laos., Economic Botany, 60(1):49-61

Missouri Botanical Garden, 2016. Tropicos database. St. Louis, Missouri, USA: Missouri Botanical Garden. http://www.tropicos.org/

PIER, 2016. Pacific Islands Ecosystems at Risk. Honolulu, USA: HEAR, University of Hawaii. http://www.hear.org/pier/index.htm

PROSEA, 2016. Plant resources of South-East Asia. http://proseanet.org/prosea/eprosea.php

PROTA, 2016. PROTA4U web database. Wageningen, Netherlands: Plant Resources of Tropical Africa. http://www.prota4u.org/search.asp

Quattrocchi U, 2006. World dictionary of grasses: common names, scientific names, eponyms, synonyms, and etymology. Boca Raton, Florida, USA: CRC Press. 2408 pp..

Rebellato L, Nunes da Cunha C, 2005. Efeito do ‘floxo sazonal mínimo da inundação sobre a composição e estrutura de um campo inundável no Pantanal de Poconé, MT, Brasil., Acta Botanica Brasileira, 19(4):789-799

The Plant List, 2013. The Plant List: a working list of all plant species. Version 1.1. London, UK: Royal Botanic Gardens, Kew. http://www.theplantlist.org

Uddin K, Juraimi AS, Ismail MR, 2012. Weed management in tropical turfgrass areas: a review., Archives of Biological Sciences, 64(2):597-603

Uddin K, Juraimi AS, Ismail MR, Brosnan JT, 2010. Characterizing weed populations in different turfgrass sites throughout the Klang Valley of western Penninsular Malaysia., Weed Technology, 24(2):173-181

USDA-ARS, 2016. Germplasm Resources Information Network (GRIN). Online Database. National Germplasm Resources Laboratory, Beltsville, USA. http://www.ars-grin.gov/cgi-bin/npgs/html/tax_search.pl

Useful Tropical Plants, 2016. Useful tropical plants database. http://tropical.theferns.info/

Vega AS, Rugólo de Agrasar ZE, 2002. Novedades taxonómicas y sinopsis del género Digitaria (Poaceae: Panicoideae: Paniceae) en Bolivia., Darwiniana, 40(1/4):171-190

Vega AS, Rugólo de Agrasar ZE, 2005. Novedades taxonómicas y sinopsis del género Digitaria (Poaceae, Panicoideae, Paniceae) en Colombia y Venezuela., Darwiniana, 43(1/4):232-267

Vega AS, Rugólo de Agrasar ZE, 2007. Novedades taxonómicas y sinopsis del género Digitaria (Poaceae, Panicoideae, Paniceae) en América Central., Darwiniana, 45(1):92-119

Zerbo I, Bernhardt-Römermann M, Ouédraogo O, Hahn K, Thiombiano A, 2016. Effects of climate and land use on herbaceous species richness and vegetation composition in West African savanna ecosystems. Journal of Botany, vol. 2016, Article ID 9523685, 11 pp. doi:10.1155/2016/9523685

Links to Websites

Contributors

23/12/2016 Original text by:

Jeanine Vélez-Gavilán, University of Puerto Rico at Mayagüez

Distribution Maps