Equisetum Hyemale – Snake Grass

Stop the spread of Equisetum hyemale (snake grass) in South Africa

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By Thulisile Jaca -Biological Invasions Directorate: South African National Biodiversity institute

Equisetum hyemale is an evergreen, slow-growing, rhizomous herb found in shaded open wet woodlands along streams and river banks. It is native throughout temperate Asia, North America, South America and Europe. It is a popular ornamental plant in temperate areas, but can be highly invasive and aggressive. E. hyemale reproduces almost entirely by rhizomes, although it also produces spores. Small pieces of tuber or rhizome broken from the parent plant can grow into new plants.

In South Africa, Equisetum hyemale was a believed to be naturalised along the banks of the Vaal River around the Emerald Casino & Vaal University in the Vanderbijlpark area. This was however confirmed to be an indigenous species, Equisetum ramosissimum.

Equisetum hyemale is listed as category 1a under NEM: BA regulations, however, no naturalised populations are known to occur in South Africa. It is known to be highly invasive when it gets into well-irrigated gardens and have the potential to become a persistent weed of wetlands, cultivated land, pastures, roadsides and other low-lying areas. If inappropriately discarded or dumped; plants may release spores or re-sprout, the underground rootstock can also regenerate metres away from the mother plant.

Equisetum hyemale can easily be confused with the indigenous species, Equisetum ramosissimum. The stems of E. hyemale are seldom branched with conspicuous ridges that makes the ridges feel rough and harsh whilst E. ramosissimum is often branched, up to 16 thinner branches arranged in whorls at the nodes with inconspicuous ridges. A table with distinguishing characters is presented below.

Character	Equisetum ramosissumum	Equisetum hyemale
Plant size	0.5-1(2) m tall 5mm in diameter	0.9 m tall and 0.8 mm in diameter
Aerial stem	Hollow, branched, longitudinally ribbed, erect	Hollow, usually unbranched, longitudinally ribbed, erect
Ridges	arc-shaped abaxially, with a row of tubercles or small light brown cross grains	arc-shaped abaxially or nearly rectangular, without conspicuous tubercles or with 2 rows of tubercles
Leaves	Scale-like, up to 10 mm, 12-16, united, with free teeth , forming a whorled sheath above each node	Scale-like, 14-50 united, with free teeth, forming a whorled ash-gray sheath above each node
Strobilus	Borne terminally on the stem with a blunt conical apex	Borne terminally on the stem with an acute conical apex

To assist with the detection and management of Equisetum hyemale, please provide us with the following information where possible:

• The locality – supply any landmarks or GPS info that will assist us to locate the plants;
• A photograph of the population and/or individual plants.
• An estimate of the surface area of invasion and/or estimated number of plants found at a particular site.

The Biological Invasions Directorate (BID) relies on the awareness and sharp eyes of you and others to achieve its success. The effort of observers is encouraged to alert the BID staff about new sightings of this target species.

If you see this invasive plant, please get in touch with us so that the infestation can be included in the overall management plan.

Contact details:

Ms Thulisile Jaca
Gauteng- North West Regional Coordinator
Tel: 012 843 5143/078 213 2738
E-mail: T.Jaca@sanbi.org.za


Ms Nkhangweleni Sikhauli
Senior Technician
Tel: 012 843 5029
E-mail: N.Sikhauli@sanbi.org.za

Alternatively, or for more information, you can email us at Invasivespecies@sanbi.org.za

References

Cooperative Research Centre for Australian Weed Management (Weed CRC). Weed Management Guide – Horsetails (Equisetum species).

Hyde, M.A., Wursten, B.T., Ballings, P. & Coates Palgrave, M. (2020). Flora of Zimbabwe: Species information: Equisetum ramosissimum subsp. ramosissimum.

https://www.zimbabweflora.co.zw/speciesdata/species.php?species_id=100210, retrieved 6 December 2020

Henderson, L. & Wilson, J.R.U. 2017. Changes in the composition and distribution of alien plants in South Africa: An update from the Southern African Plant Invaders Atlas. Bothalia 47(2), a2172.

Lansdown, R.V. 2014. Equisetum hyemale. The IUCN Red List of Threatened Species 2014: e.T203003A42381564. http://dx.doi.org/10.2305/IUCN.UK.2014-1.RLTS.T203003A42381564.en.

Large, M.F., Blanchon, D.J. & Angus M.L. 2006. Devitalisation of imported horsetail (Equisetum hyemale). New Zealand Journal of Crop and Horticultural Science 34: 151–153.