Nardoo (Marsilea drummondii
) is a perennial fern that grows quickly in water and mud found along areas with poor drainage and edges of inland lakes, roadside drains, rivers, or other water sources following a flooding. M. drummondii
resembles a four-leaf clover, and produces spores which germinate in response to moist environments.
All parts of M. drummondii
contain very high amounts of thiaminase during the early stages of their growth. Thiaminase is the same toxin that is found in bracken fern (Pteridium aquilinum)
, which results in bracken fern toxicity
. Horses are most at risk of poisoning from consumption of M. drummondii
following a flood or heavy rain.