SafePlants

Sleepy Grass (Achnatherum robustum)

Achnatherum robustum, commonly known as sleepy grass, is a perennial grass that has gained notoriety for its effects on grazing animals. The common name reflects its ability to induce drowsiness and stupor, particularly in horses.

Considerations for Pets

• Sleepy grass is often infected with a fungus that contains LSA and other related compounds.
• When infected with certain fungal species (of the genus Neotyphodium and/or Acremonium), it is known to cause drowsiness and stupor in grazing animals, particularly horses.

Taxonomy and Nomenclature

• Scientific Name: Achnatherum robustum
• Common Name: Sleepy grass
• Synonyms: Stipa robusta, Stipa vaseyi subsp. robusta
• Family: Poaceae (Grass family)

Distribution and Habitat

• Sleepy grass is native to Colorado and New Mexico.
• Various species of the genus Stipa, to which it was formerly assigned, are found from Texas to Guatemala.
• It is found in the White Mountains of the region of the Rio Grande.
• It thrives at higher elevations, such as the Sleepy Grass Campground at 8800 feet.

Ecological Role

• The plant's toxicity is linked to fungal endophytes that reside within it.
• The presence of these microbes turns the grass toxic, causing a sedating effect on animals.

Morphological Characteristics

• It is a large plant with straight spikes that can grow up to 5 feet tall.

Interactions with Other Organisms

• Sleepy grass is often infected with an Acremonium fungus.
• This fungus contains LSA and other related compounds, causing drowsiness and stupor.
• Researchers are studying the alkaloids of Stipa robusta infected with an Acremonium endophyte.
• Research suggests the plant's endophytes influence its resistance to insects.

Quirky Facts

• The sedating effect of sleepy grass on animals is not a new discovery; it was documented in Science journal as early as 1903.
• The "sleepy" nature of the grass has inspired names for campgrounds and properties in areas where it grows.

Further Information

• More information can be found in articles from Science, Volume 17.
• Additional data can be found at ResearchGate, Encyclopedia.com, and RealtyTrac.
• There is an article titled "Sleepy Grass and Its Effect on Horses" published in Science (Science 06 Mar 1903: Vol. 17, Issue 427, pp. 392-393).