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Spartina densiflora

Perennial grass, rhizomatous, present on the sludge of low tides.

Scientific name: Spartina densiflora Brongon.

Common names: dense-flowered cordgrass, austral cordgrass

Family: Poaceae (Gramineae)

Status in Portugal: invasive species (listed in the Decreto-Lei nº 92/2019, 10 july)

Risk Assessment score: 14 | Value obtained according to a protocol adapted from the Australian Weed Risk Assessment (Pheloung et al. 1999), by Morais et al. (2017), according to which values above 13 mean that the species has risk of having invasive behavior in the Portuguese territory | Updated on 30/09/2017.

Synonymy: Chauvinia chilensis Steud., Spartina densiflora Brongn. var. typica St.-Yves subv. brongniartii St.-Yves, Spartina densiflora Brongn. var. typica St.-Yves, nom inval., Spartina densiflora Brongn. var. typical St.-Yves subv. pauper St.-Yves, Spartina juncea Willd. var. laxiflora St.Y.ves, Spartina juncea Willd. var. montevidensis (Arechav.) St.-Yves, Spartina montevidensis Arechav., Spartina patagonica Speg.

Last update: 08/07/2021

Family: 
Poaceae (Gramineae)
Appearence: 
Grasses and herbs

How to recognise it

Rhizomatous grass that forms a dense tuft. Culms from up to 150 cm, glabrous, robust.

Leaves: in-rolled, with 3-8 mm wide when flat.

Flowers: spikelets with 1 (rarely 2) flowers, 7-10 mm, greenish, in turn arranged in spikes generally overlapped and tightly appressed to the axis, linear, 3-6 cm, arranged (2-15) in 10-30 cm erect inflorescences; glabrous or puberulent chaffs, lanceolate, with 1 scabrid vein, the inferior one 1,5-4 mm, the superior one 7-14 mm.

Fruits: linear caryopses.

Flowering: June to December.

 

Similar species

Spartina patens (Aiton) Muhl., frequent in the same type of habitats, is fairly similar, but it forms a coarser tuft, with a creeping rhizome; the leaves are wider (0,8-1,5 mm); the spikelets are smaller than 7 mm, in turn arranged (2 a 6) in inflorescences with 10-16 cm.

 

Characteristics that aid invasion

It propagates vegetatively through stem fragments that root easily.

It also reproduces by seed; it produces many seeds (around 2000 seeds/plant) that are dispersed through the water, favouring the expansion of the invaded area.

Native distribution area

South America (Chile).

 

Distribution in Portugal

Mainland Portugal (Algarve). There are some references of its distribution in the North.

 

Geographic areas where there are records of Spartina densiflora

Other places where the species is invasive

Europe (Spain), western USA (California), Africa (Morocco).

 

Introduction reasons

Probably accidental.

 

Preferential invasion environments

It shows an enormous ecologic adaptability, being able to thrive in different environmental conditions (salinity, flooding) and habitats.

Maritime medium and low tide sludge’s. It also appears in estuaries.

It develops in poorly drained soils or disturbed locations where the drainage conditions or sediment accumulation patterns have altered.

 

Impacts on ecossystems

It grows rapidly, forming very dense and impenetrable populations, which prevent the development of native vegetation.

 

Economic impacts

High costs in the application of control methodologies.

 

Natura 2000 network habitats more subject to impacts

– Estuaries (1130);
– Spartina swards Spartina (Spartinion maritimae) (1320);
– Atlantic salt meadows (Glauco-Puccinellietalia maritimae) (1330);
– Mediterranean salt meadows (Juncetalia maritimae) (1410);
– Mediterranean and thermo-Atlantic halophilous scrubs (Sarcocornetea fruticosi) (1420).

Controlling an invasive species demands a well-planned management, which includes the determination of the invaded area, identifying the causes of invasion, assessing the impacts, defining the intervention priorities, selecting the adequate control methodologies and their application. Afterwards it is fundamental to monitor the efficiency of the methodologies and recuperation of the intervened area as to perform, whenever necessary, the follow-up control.

The control methodologies used for Spartina densiflora include:

 

Physical control

Manual/mechanical pulling: preferential methodology for invaded areas of small dimensions. In compacted substrates, the pulling should be made in the rain season as to facilitate the removal of the root system. It should be guaranteed that no large rhizomes or fragments are left in the ground.

Cutting: preferential methodology for large invaded areas. Cutting the aerial part should be done with mechanical equipment (such as brushcutters).

 

Chemical control

Foliar application of herbicide. Herbicide spray (active substance: glyphosate in formulas adapted for aquatic environments) limiting the exposure to the target species.

 

Visit the webpage How to Control for additional and more detailed information about the correct application of these methodologies.

Bortolus A (2006) The austral cordgrass Spartina densiflora Brong.: Its taxonomy, biogeography and natural history. Journal of Biogeography 33: 158-168.

 

 

Capdevila-Argüelles L, Zilletti B, Álvarez VAS (2011) Cambio climático y especies exóticas invasoras en España. Diagnóstico preliminar y bases de conocimiento sobre impacto y vulnerabilidad. Oficina Española de Cambio Climático, Ministerio de Medio Ambiente y Medio Rural y Marino, Madrid, 146 pp.

 

 

 

 

Faber P (2000) Spartina densiflora. In: Bossard CC, Randall JM, Hoshovsky MC invasive">Invasive Plants of California’s Wildlands. University of California Press, Berkeley, CA.  pp. 295-299.

 

 

 

 

Global invasive">Invasive species">Species Database (2012) Spartina densiflora. Available: http://www.issg.org/database/species/ecology.asp?si=1372&fr=1&sts=&lang=EN [Retrieved 12/11/2012].

 

 

 

 

Marchante E, Freitas H, Marchante H (2008) Guia prático para a identificação de plantas invasoras de Portugal Continental. Imprensa da Universidade de Coimbra, Coimbra, 183pp.

 

 

 

 

Pickart A (2005) Control of invasive Spartina densiflora in a high-elevation salt marsh, Mad River Slough, Humboldt Bay National Wildlife Refuge. U. S. Fish and Wildlife Service, Arcata, California, 15 pp.

 

 

 

 

Zedler JB, Kercher S (2004) Causes and consequences of invasive plants in wetlands: Opportunities, opportunists, and outcomes. Critical Reviews in Plant Sciences 23(5): 431-452.