Marsilea hirsuta

Marsilea hirsuta is a semi-aquatic fern native to temporary pools, swamps, and the seasonally inundated floodplains of Australia, where it is adapted to survive periodic drying and flooding. This remarkable adaptation makes it extraordinarily hardy in aquarium conditions — it can endure a wide range of temperatures, moderate water hardness, and reduced lighting without perishing, making it one of the most beginner-friendly true carpet plants available. Submerged, it produces characteristic four-lobed, clover-like leaves on thin petioles, each looking like a miniature four-leaf clover. Depending on conditions, these leaves may be held upright (petiole visible) under lower light, or pressed flat to the substrate forming a denser carpet under high light. In the aquarium it spreads slowly but steadily via rhizome, eventually forming a charming, irregular carpet that provides a distinct visual contrast to grass-type plants. It pairs particularly well with hairgrass, mosses, and small Anubias in low-tech or nature-style layouts. Its unusual leaf form adds botanical diversity and often sparks curiosity from visitors unfamiliar with aquatic ferns.