Quick Facts

Quick facts

• Originally from the northern hemisphere, Horsetails (Equisetum spp.) are one of the world's worst weeds.
• They are not native to Australia and have the capacity to damage both native biodiversity and agriculture if they become established.
• Horsetails are extremely invasive and difficult to control. Prevention and early intervention is the most effective control method.
• Despite their desirability for landscaping and herbal medicine they should not be planted in gardens.
• If this species is seen it should be reported the relevant weed management authority. Do not attempt to control on your own.

What Does It Look Like?

What is it?

Horsetails (Equisetum secies.) are a non-flowering perennial plant related to ferns. There are 30 species world-wide, of which 12 are considered weedy, with only two, Equisetum arvense and Equisetum hyemale recorded as a weed or potential weed outside cultivation in Australia. They produce two different kinds of shoots from long underground stems called rhizomes. Sterile green hollow stems are produced develop with leaves, and fertile pale brown fronds bearing fruiting cones. This fertile branches emerge in spring and die after shedding spores. Both kinds of shoots break easily at the joints (CRC 2003; Groves et al. 2005). The stems are hollow and segmented and grooved longitudinal. Inconspicuous small leaves on the main shoots grow in rings of 6 to18,  joined at their edges to form a black-tipped sheath of sharp teeth (these are the leaves) around the stem (CRC 2003). The branches and leaves of Equisetum remind many people of the branches and leaves of Casuarina  and Allocasuarina (the sheoaks).  The pale brown fertile fronds bearing fruiting cones emerge in spring and die after shedding spores. The roots or rhizomes (underground stem that function as roots) give rise to other stems and if broken off from the parent plants and transported to suitable conditions elsewhere can form new plants.  Roots have been recorded to depths of 2 meters and spread many more across (sideways), with roots known to break through bitumen and concrete. 

The Common Horsetail (Equisetum arvense) shoots usually die back over winter. However, above ground growth may persist over the winter months in other species (CRC 2003).

Scouring Rush Horsetail (Equisetum hyemale) was given its common name due to the high silica content in the plant tissues (CRC 2003). The shoots have been used to scour pots and pans (Weeds Australia). 

For further information and assistance with identification of Horsetails contact the herbarium in your state or territory.

Flower colour

None 

Growth form (weed type/habit)

Herb, Aquatic

Where it currently grows? Preferred habitat

Horsetails generally require moist conditions to establish but can then persist in a wide range of climates due to a number of adaptations which help to increase water use efficiency: a waterproof outer layer; green stems; and special pores in the leaves. In drier areas the plants greatly reduce the size of their leaves to minimise water loss (CRC 2003). Tolerant to waterlogging, salinity, frost, & fire (rhizomes survive), but it is not drought tolerant.

Most species inhabit swampy areas such as the edges of lakes, rivers and creeks, and prefer disturbed sites. They grow on many types of soil and can tolerate low nutrient levels (CRC 2003). While they prefer wet areas they can move into well-drained soil through vegetative reproduction (Hartzler 2006).

Common Horsetail (E. arvense) usually grows in damp, open woodlands, pastures, arable lands, roadsides, stream banks and embankments. It will grow in most wet places below altitudes of 300 m. It is a weed in Australia in areas where the annual rainfall is around 1400 mm.

Scouring Rush Horsetail (E. hyemale) similarly occurs on moist or springy grasslands, banks and roadsides, and is naturalised in New South Wales in areas below altitudes of 620 m with annual rainfall of 1100-1500 mm (CRC 2003).

Are there similar species?

There are no similar species

Why Is It A Weed?

What are its impacts?

Horsetails are on the Alert List for Environmental Weeds, a list of 28 non-native plants that threaten biodiversity and cause other environmental damage. Although only in the early stages of establishment, Horsetails have the potential to seriously degrade Australia's ecosystems (CRC 2003). Horsetails are highly invasive, difficult to control and toxic to livestock. They can be allelopathic.

Native ecosystems: Horsetails are known as one of the world's worst weeds and are highly invasive. In Sydney they have infested hundreds of square metres along creek lines. They have the potential to become persistent weeds of wetlands and other low-lying areas. Large areas of natural vegetation are potentially under threat (CRC 2003).

Agriculture: Horsetails are highly toxic to livestock. If consumed in contaminated hay it has been known to kill horses, cattle and sheep (CRC 2003). Most Equisetum species contain poisonous glycosides in the rhizomes and aerial shoots. Equisetum arvense also contains alkaloids that make it toxic to horses, causing a syndrome (equisetosis) that is sometimes fatal.Part of its action may be due to the enzyme thiaminase that destroys thiamine (vitamin B1) in the stomach of the animal.It has also caused losses in sheep and cattle and is reputed to taint milk when eaten in quantity (Government of South Australia 2021). In high densities, Horsetails reduce crop yields by producing inhibitory substances that depress the growth of neighbouring plants (CRC 2003). Equisetum species are also competitive and persistent weeds of crops and pastures in the Northern Hemisphere. Horsetails are of particular concern to the canola, cereals, lupin, apple and pear, and potato growing industries and as a nursery weed (Groves et al. 2005).

How does it spread?

Horsetails produce millions of tiny spores that are dispersed by wind and water. However, most of these spores do not survive as they require prolonged moist conditions (such as in wetlands) to germinate. Most of the spread of Horsetails occurs by rhizomes. A piece of the rhizome or tuber broken off the parent plant can grow into a new plant. As a result Horsetail fragments can easily be carried in soil or transported by construction equipment to new areas. They can also be distributed through the dumping of garden rubbish and contaminated soil, or during road making activities (CRC 2003).

It is possible that Common Horsetail was introduced into New Zealand in the soil surrounding the roots of Iris commercially imported from Japan (Csurhes & Edwards 1998). The rhizomes of one individual can grow extensively, eventually reaching 30 m wide and up to 5 m deep (CRC 2003) although without soil disturbance this growth is relatively slow (Hartzler 2006).

What is its history in Australia?

Horsetails are popular as interesting foliage plants in landscaping around the world and were almost certainly introduced as ornamental plants. An outbreak was recorded from an Adelaide plant nursery in the 1950s (CRC 2003).

 Scouring Rush Horsetail (E. hyemale) has been introduced for use by herbalists in Tasmania since the 1970s despite being listed as a noxious weed in state legislation (Rozefelds et al. 1999). They are also promoted for use in biodynamic preparations. 

How To Manage It?

Best practice management

Prevention: Because there are relatively few Horsetail infestations, and they can potentially be eradicated before they become established, any new outbreaks should be reported immediately to your state or territory weed management agency or local council. Do not try to control Horsetail without their expert assistance. Control effort that is poorly performed or not followed up can actually help spread the weed and worsen the problem (CRC 2003).

Non-chemical control: Horsetails are extremely difficult to control once established. Their extensive and deep system of rhizomes makes physical removal difficult. They also re-establish easily from root fragments so even leaving small pieces behind in a cleared site will lead to re occurrence of the plants (CRC 2003; Groves et al. 2005).

Chemical control: Non-specific herbicides are not effective against Horsetails. Check with your local council or state or territory weed management agency for relevant control advice in your area (CRC 2003).

See the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au .

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

In Australia fertile shoots appear in early spring. Spores are released and germination occurs, assuming conditions are favorable, during summer. Growth of the sterile shoots from established plants occurs from early spring until autumn. Rhizome growth occurs during the same time. Tubers initiated during late summer grow in size and number until late autumn, providing stored energy to be used in harsh conditions (CRC 2003).

Where Is It Found?

Which states and territories is it found?

NSW

What areas within states and territories is it found?

Horsetails have been grown and sold as ornamental plants throughout Australia (NSW DPI 2019). While Horsetails have been found in a number of sites from Tasmania to Brisbane (CRC 2003) they are thought to have only naturalised in New South Wales (APC 2021; AVH 2021). Infestations have been recorded north of Sydney at Narrabeen Lakes, Belrose, and at Snake Creek, Bayview Heights, infesting hundreds of square metres along creek lines at these sites (CRC 2003).

Scouring Rush Horsetail (E. hyemale) is naturalised in New South Wales in areas below altitudes of 620 m with annual rainfall of 1100-1500 mm. Branched Horsetail Equisetum giganteum  [as E. ramosissimum] has become a garden weed in New South Wales by outgrowing the garden areas where it was planted. Outbreaks of Scouring Rush Horsetail and Branched Horsetail are currently under control (CRC 2003).

Where does it originate?

This genus is mostly native to temperate regions of the northern hemisphere (CRC 2003), although one species is found as far south as New Guinea (Croft 1986). Common Horsetail, the most common species found in Australia, is a native of Great Britain, Europe, Asia and North America (Groves et al. 2005).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

Declared in all Australian states and territories

Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?

YES

Government weed strategies and lists – Weeds Australia

Is it on the Agricultural Sleeper List?

NO

Government weed strategies and lists – Weeds Australia

Names And Taxonomy

Main scientific name

Equisetum spp.

Other scientific names (synonyms)?

Does it have other known common name(s)?

Scouring Rush, Field Horsetail, Common Horsetail, Western Horsetail, Foxtail, Horsetail Fern, Meadow Pine, Pine Grass, Fox Tail Rush, Bottle Brush, Horsepipes, Snake Grass, Mare's Tail, Shave Grass, Coda Cavallina