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.

Placement Plant in the foreground, spacing individual plants 3–4 cm apart. It spreads slowly so patience is required for full coverage. Works well around rock and wood bases in nature aquarium designs.

Lighting Adaptable from low to high lighting (20–80 PAR). Under low light it produces upright, taller growth; under high light the leaves flatten to the substrate forming a tighter carpet. Even moderate light is sufficient for healthy growth.

CO2 & Fertilisation Does not require CO2 injection, making it one of the few carpet plants viable in low-tech setups. Root tabs or a nutrient-rich substrate help accelerate spreading. Light liquid fertiliser once a week is adequate.

Propagation Propagates via rhizome runners. Individual plants on runners can be cut and moved to new areas. The rhizome can also be divided and replanted in fresh substrate.

Trimming Minimal trimming is required due to the plant's short, compact growth. Remove any overlong petioles that make the carpet look uneven. Thin the carpet occasionally if growth becomes excessively dense.