Common Horsetail

Equisetum arvense L.

Synonyms -

Family: - Equisetaceae

Names:

Equisetum is from the Latin equis for horse and setum for bristle or hair.

Arvense is from the Latin arvum meaning ploughed or cultivated field.

Horsetail refers to the stems when bunched together looks like a horse's tail.

Other Names:

Acker-Schactelhalm (Germany), Bibitungan (Sunda), Bottlebrush, Bull Pipes, Corn Horsetail, Devil's Guts, Field Horsetail (USA), Foxtail, Rush, Helecho (Chile), Horse Fern, Horse Pipes, Jointgrass, Joint weed, Mares Tail, Meadowpine, Paddock-pipes, Peltokorte (Finland), Prele des Champs (France), Pewterwort, Pine-grass, Rough Horsetail, Scouring Rush (USA), Shavegrass, Snake-grass, Sugina (Japan), Tropongan (Java)

Scouringrush refers to its use for scouring pots and pans


Summary:

An erect, rhizomatous, colony forming perennial herb 10-60 cm tall, with distinctive, erect, grooved stems with whorls of branches that often die back over summer. It reproduces by spores, tubers and rhizomes. It is related to the ferns.

Description:

Cotyledons:

Two.

First leaves:

Leaves:

Usually green on the main stem but often dark brown on the lower stem. They are in whorls of 6-18 corresponding to the stem grooves and fused lengthwise to form a cup shaped sheath that is 5-8 mm long with 2-3 mm long teeth on the sterile stems. Sheaths on the unbranched fertile stem are 14-20 mm long.

Blade - 7-11 mm long on sterile stems.

Long thin needle like branches look like leaves.

Stems:

Usually annual. Erect or low lying (decumbent) and jointed.

Two types
  1. Fertile whitish stems appearing in spring, 8 mm diameter and less than 300 mm tall, somewhat succulent, unbranched, jointed and with brownish cylindrical and toothed nodal sheaths that are 14-20 mm long. These produce a long-stalked spore producing cone (strobilus) and die off in summer when the spores are released.
  2. Sterile green stems appear in late spring after the fertile stems and are <500 mm high, 1.5-5 mm diameter, hollow and grooved. They form whorls of 3-4 angled solid branches arising below the cup shaped sheaths at the nodes.
Flower head: (Strobilus)

The strobilus is pale green, 10-40 mm long, formed by many stalked scales (sporangiophores) each bearing 5-10 reflexed, spore forming sporangia.

The strobilus forms at the ends of fertile stems.

Flowers:

No flowers.

Fruit:

No Fruit.

Seeds: (Spores)

Pale green to yellow, globular, each with a pair of spoon shaped elators.

Roots:

Wiry, usually annual, rising in groups from the base of lateral branch buds and erect shoots along the extensive rhizomes and generally within 1 m of the soil surface.

Rhizomes are dark brown to black and from the surface to several metres deep and generally horizontally growing to over 10 m. They are hairy and felted at the nodes. The underground rhizomes also give rise to small, round, starch filled tubers.



Root structure of Equisetum arvense
Courtesy Bill Parsons

Key Characters:


Biology:

Life cycle:

It has free living sexual and asexual reproductive generations. Common horse tail is the diploid plant or sporophyte which produces haploid asexual spores.

These thin walled, short lived spores germinate producing free living, haploid gametophytes which are very small, green cushion like organs that are male or female. The darker green female gametophyte forms egg producing archegonia but may become bisexual and form spore producing antheridia. The lighter green male gametophyte only forms antheridia. Multiflagellate motile sperm from the antheridia fertilise the single egg in the archegonium if moisture is present. The sexually produced oospores thus formed germinate and the sporelings develop into the fertile and sterile stems and rhizome system of the diploid sporophyte generation. The fertile stems form strobili and the haploid spores by meiosis.

The rhizomes bud off tubers which form new stems during the growing season.

Shoot growth starts in spring reaching a maximum in summer and has the maximum shoot number in autumn followed by dying off over winter. The rhizome growth follows a similar pattern, establishing a layered system extending 30 m laterally and more than 5 m vertically. About half the rhizome system is in the top 25 cm of soil and a quarter in the next 25 cm of soil and the rest deeper to 5 m. Tubers form in late summer and increase in size and number over autumn. About half the tubers are more than 50 cm deep in the soil.

Physiology:

It accumulates silica in the epidermal cells which gives it the gritty feel and use as a scourer.

Also accumulates gold, copper, zinc, cadmium and lead and may be used as an indicator plant for presence of heavy metals.

Reproduction:

By spores and vegetatively from tuber and rhizome segments.

Flowering times:

Late spring to summer.

Seed Biology and Germination:

Spores must germinate almost immediately and require most conditions. The gametophyte can live for 2 years in the lab, but most die from desiccation in the field. There may be self inhibition of spore germination within the colony.

Vegetative Propagules:

Rhizomes and tubers

Hybrids:

Some species can form hybrids.

Allelopathy:

Population Dynamics and Dispersal:

Most of the dispersal is by intentional planting of rhizomes or tubers purchased from nurseries or from these organs being moved by earthworks.

Some movement occurs by spore dispersal which may be aided by the elators on the spores that move with changes in humidity.

Origin and History:

Native to North America, Europe and Asia.

The Equisetums have been around since the Carboniferous period.


Distribution:

Equisetum arvense NSW, VIC.

Equisetum hyemale NSW, TAS, VIC, WA.



Equisetum arvense
Courtesy Australia's Virtual Herbarium.



Equisetum hyemale
Courtesy Australia's Virtual Herbarium.

Habitats:

Climate:

Cold to warm temperate regions with temperature from <50C to >200C and an annual rainfall of 100-2000 mm.

Frost tolerant. Sensitive to drought.

Soil:

Prefers neutral to slightly alkaline gravelly sands to silty clay loams but will tolerate acid soils.

Prefer wet areas.

Plant Associations:

Open woodlands.

Significance:

Beneficial:

Used as a scourer, sand paper and a source of dye. When boiled and dried it is used as a polish.

Used for erosion control on embankments.

Used in folk medicine as a diuretic, for haemorrhage control, fungal diseases and sore mouths.

Detrimental:

Weed of market gardens, orchards, cereal, flax, potatoes, nurseries, pastures, roadsides, embankments, steam banks, damp open woodlands and low lying areas.

It is listed as one of the world's worst weeds.

Toxic.

Toxicity:

Toxic to stock.

It causes equisitosis which is related to a number of alkaloids including palustrine an equisitine which destroy thiamine causing vitamin B deficiency.

Sheep and cattle are most affected by eating green material and horses from eating dry material in hay.

Symptoms:

Weakness of the hindquarters, excitability, lack of coordination, trembling, increased heart rate, convulsions, coma and death have been recorded.

Treatment:

Remove stock from infested areas. Treat with large doses of thiamine.

Spraying infested areas with 2,4-D or MCPA reduced the toxicity of the area.

Legislation:

Declared weed of all states and the NT in Australia.

Management and Control:

Cultivation, burning and slashing are ineffective.

Lowering water tables and lengthy solarisation with black plastic has provided some control.

Hormone herbicides control aerial growth but it soon regrows. MCPA gave better control than 2,4-D and best result occurred after all shoots had emerged.

Amitrole T, chlorsulfuron, dichlobenil, flumetsulam, halosulfuron, hexazinone, linuron, MCPA and triclopyr have had the best results.

Subsurface placement of dichlobenil or MCPA has provided better rhizome control than surface sprays.

Thresholds:

50-60 fronds/m2 reduces maize yields.

Lower densities interfere with crop harvesting.

In pastures low levels may cause stock toxicity.

Eradication strategies:

It is difficult to eradicate.

The USA uses 60 kg/ha watered in as a pre em application each year for 3 years. Repeated MCPA is used for post emergence applications with about 30% control achieved at each application. Each repeat must occur before the Horsetail replenishes the rhizome.

Herbicide resistance:

None reported

Biological Control:

Fungal pathogens are being studied in Italy.

Related plants:

Equisetum bogatensis

Equisetum hyemale (Scouringrush Horsetail) is under eradication at Wanneroo and Bedfordale near Perth in WA

Equisetum palustre Marsh Horsetail is one of the world's worst weeds.

Equisetum ramosissimum

Equisetum scirpoides

Equisetum

Equisetum

Plants of similar appearance:

Young Allocasuarina or Casuarina.

Some members of the Restionaceae such as Restio tetraphyllus and R. australis.

Some ornamental Elegia species.

References:

Bodkin, F. (1986). Encyclopaedia Botanica. (Angus and Robertson, Australia).

Blood, K. (2001). Environmental weeds: a field guide for SE Australia. (CH Jerram & Associates, Australia). P142-143. Photos.

Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney).

Harden, Gwen J. (1991). Flora of NSW. (Royal Botanic Gardens, Sydney). Volume 1. P12. Diagram.

Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J. and Lloyd, S.G. (2007). Western Weeds. A guide to the weeds of Western Australia. (Second Edition). Plant Protection Society of Western Australia, Perth, Western Australia. P265.

Lazarides, M. and Cowley, K. and Hohnen, P. (1997). CSIRO handbook of Australian Weeds. (CSIRO, Melbourne). 388.2

Parsons, W.T. and Cuthbertson, E.G. (1992) Noxious weeds of Australia. (Inkata Press, Melbourne). P14-17. Photos.

Randall, J.M. and Marinelli, J. (1996) Invasive Plants. (Brooklyn Botanic Gardens Inc. Brooklyn). P. Photo.

Roy, B., Popay, I., Champion, P., James, T. and Rahman, A. (1998). An Illustrated Guide to Common Weeds of New Zealand. (New Zealand Plant Protection Society). P151. Photo.

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.