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Snake Grass (Equisetum hyemale)

Snake grass, Equisetum hyemale, is an erect, evergreen, perennial herb whose stems can grow between 30 and 120 cm tall. 

It reproduces through spores and can spread through creeping rhizomes to form large colonies. 

You can identify the plant by its bamboo-like medium to dark-green stems. The stems are hollow, jointed, and segmented and have vertical ridges that are full of silica. 

Scientific Classification

  • Domain: Eukaryota
  • Kingdom: Plantae
  • Phylum: Tracheophyta / Sphenophyta
  • Subphylum: Pteridophyta 
  • Class: Equisetopsida
  • Order: Equisetales
  • Family: Equisetaceae
  • Genus: Equisetum
  • Species: Equisetum hyemale
  • Subspecies: Equisetum hyemale subsp. affine
  • Common Names: rough horsetail, scouringrush horsetail, scouring rush, Dutch rush 

Nativity & Distribution

Snake grass is native to North America, Europe, and northern Asia. It can also be found in: 

  • South Africa
  • Australia
  • New Zealand

Physical Characteristics

The evergreen snake grass has bamboo-like stems and can grow up to a height of 1.2 m
The evergreen snake grass has bamboo-like stems and can grow up to a height of 1.2m. Image: Flickr/blueridgek
  • Leaves: Small greyish leaves surrounding (and clasp) the stem at the nodes. 
  • Fruits: No fruits. Instead, the plant produces cones at the stem’s tip. 
  • Stems: Erect, green, unbranched stem. It can grow to between 30 and 120 cm tall. 
  • Flowers: It produces no flowers. 
  • Roots: Branched, creeping rhizomes. They grow to depths of four feet (or more). 

Equisetum hyemale is a perennial herb that grows erect and can reach up to 1.2 m in height. It is easily recognized by its green (medium to dark green) stems, which look like bamboo. 

The stems are round, about 4 to 6 mm thick, and hollow inside. They are usually unbranched and have ridges that are full of silica, giving them a rough, grooved surface. 

The snake grass stems are evergreen and persist even through the winter. However, they eventually dry, turning brown before withering away. 

Equisetum hyemale does not have true leaves. Instead, the herb has leaf sheaths around the stem at the nodes. The leaf sheath is greyish, with around 14-50 tiny teeth-like fringes.

A thin, black band also forms above and below the leaf sheath. As the season progresses, the grey “leaves” fall off, leaving just the black rings around the top and bottom of the sheath.

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Note: Due to the lack of true leaves, the photosynthesis functions are carried out in the stems. 

Snake grass does not produce flowers or seeds. However, the plant does bear cones, which emerge at the tip of the stems. 

The pine-like cones are about 8-15 mm long and rounded at the tip but feature a small, sharp, black-tinged tip.  

Reproduction, Dispersal, & Life Cycle

  • Life Cycle: Perennial
  • Seeds: No seeds. The plant reproduces sexually through spores
  • Climate: Grows well in areas with tropical, subtropical, monsoonal, and temperate climates
  • Dispersal: Wind (spores) and creeping rhizomes 

Equisetum hyemale reproduces sexually through spores. The spores are formed at the cones, which emerge in spring and then die after the spores have been shed. 

Snake grass spores can be dispersed by wind. They can also travel along the ground until they find a suitable habitat. 

They (spores) germinate in a wet environment; therefore, the plant is considered semi-aquatic. 

When the shed spores land in a moist environment, they germinate and develop into gametophytes, forming specialized sex organs that produce sperm and eggs. 

The plant’s fertilization process takes place in water. The sperm released by one gametophyte swims through water to reach the eggs of another gametophyte. 

The fertilized egg then develops into zygotes, sporophytes, and, ultimately, independent plants. 

Even though Equisetum hyemale may reproduce sexually, its main method of spreading is asexually, especially through creeping rhizomes. 

The rhizomes spread far and wide, sending new shoots from the soil that form new plants. 

Snake grass rhizomes can also break apart naturally or through soil disturbances. Any new fragment that contains a node and a bud can form a new plant. 

Lastly, new plants can also emerge from cuttings of the Equisetum hyemale stems. 

Uses

  1. Snake grass is a medicinal plant because of its anti-inflammatory and diuretic properties.
  2. It is planted in landscapes as an ornamental plant. 
  3. Because of its rough stems, the plant is used as a polishing material, sandpaper, and pot scouring (cleaning) material. 
  4. Dried stems are used to make reeds for musical instruments. 
  5. It can be used to stabilize soils and prevent soil erosion because of its deep root system. 
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Impact on Environment

Snake grass is a quick-growing weed that can overtake crop fields and suffocate native vegetation
Snake grass is a quick-growing weed that can overtake crop fields and suffocate native vegetation. Image: Canva/miazeus

Equisetum hyemale is considered an invasive weed in several areas, including Australia and South Africa. Once the plant has infested a new area, it can quickly spread, invading crop fields, pastures, and native vegetation. 

In heavy infestation, snake grass can suffocate native plants, reduce crop yields, and make pastures less productive. 

It can also become a persistent weed in wetlands and other low-lying areas; for example, in Australia, it has infested large areas of the creek lines.  

Equisetum hyemale rhizomes and shoots contain glycosides, which are toxic and potentially fatal to animals. The silica particles in the stems can also irritate and sicken livestock. 

What makes snake grass even more dangerous is the fact that it is very difficult to eradicate. The deep-growing rhizomes are very hard to remove (completely) from the soil, meaning the weed can return repeatedly.

It can also easily establish new colonies through spores, cuttings, splits, branches, or other plant parts that fall off. 

Control

Control methods for the snake grass include:

  • Natural methods: Repeated tillage and mechanical removal. 
  • Chemical control: Selective and non-selective herbicides. 
  • Cultural control: Improving drainage, boosting soil fertility, and raising PH. 

1. Cultural control

The best method for controlling Equisetum hyemale is prevention. Cultural control solutions that alter the growing conditions can make this possible by making the environment inhabitable for snake grass. 

For example, since snake grass thrives in wet environments, improving drainage can reduce its vigor. 

Raising the soil’s pH by adding agricultural lime can make an area less suitable for snake grass infestation, as the plant prefers acidic soils. 

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Boosting soil fertility (compost, chemical fertilizers, etc.) to increase the competitiveness of crops is another excellent cultural control tip that can prevent infestation of Equisetum hyemale

2. Natural control

In the event of an infestation, you can try natural control solutions like repeated tillage or mowing. These help eliminate the top growth, thus preventing spores from germinating. 

Repeatedly cutting the green growth can also overwhelm the plant and deplete its carbohydrate reserves, causing it to die over time. 

Unfortunately, this is time-consuming and can take years, especially if you have a large infestation. 

Physical removal of the plant (including the rhizome) is another option. This can work if you have a small infestation that has not formed a deep root system. 

However, for large infestations, physical removal might only be possible through excavation to ensure that you remove the entire rhizome system. 

One thing to note is that mowing, tilling, and physically removing the rhizomes can further spread the weed. 

Therefore, you must carefully dispose of the removed plant parts in a sealed plastic bag and ensure no fragments are left in the soil. 

You can also dispose of the removed plants by incinerating them. Unfortunately, burning the snake grass infestation is not a recommended control method, as it will not eliminate the rhizomes in the soil.

3. Chemical control 

Chemical control of Equisetum hyemale is also possible through selective and non-selective herbicides. Excellent options include broad-spectrum herbicides like glyphosate or contact herbicides like diquat. 

You can also use Telar (chlorsulfuron), a selective herbicide, for non-crop areas (roadsides, fencerows, etc.) or SedgeHammer (halosulfuron) for turf areas. 

For cropland areas, you can also try herbicides like flumetsulam (Python, Hornet). 

One thing to note regarding chemical control is that snake grass does not have true leaves, making it hard to apply foliar herbicides.

In addition, the high silica content in the stems can interfere with the uptake of herbicides. 

Therefore, you must plan carefully and consult a professional before using chemical herbicides to control Equisetum hyemale