Cardamine lyrata (Japanese Cress)

Cardamine lyrata, Japanese Cress, is a versatile cool-to-temperate aquatic plant from East Asia that grows both submerged and emergent with equal ease. In its emergent form it produces lobed, bright-green leaves reminiscent of its relative the garden cress, and bears clusters of tiny white four-petalled flowers that add a meadow-like quality to the riparian zone. The plant spreads by producing adventitious plantlets along the stem that drop off and establish independently — a feature that makes it a prolific self-propagator.

It is one of the most cold-tolerant emergent aquatic plants, thriving in cool paludariums where many tropical species would fail. It is equally effective in the transition zone of temperate stream or pond-style paludariums. Under warm conditions it grows quickly and may require more frequent trimming, but the cut stems and self-generated plantlets ensure there is always abundant replacement material.

Light: Medium indirect; 1,500–3,500 lux; tolerates lower light but flowering is reduced. CO2/Humidity: No CO2; roots in water or saturated substrate; emergent stems in ambient humid air. Fertilisation: Monthly dilute all-purpose fertiliser into the water section. Placement: Plant in substrate at the waterline; adventitious plantlets will colonise surrounding areas naturally. Propagation: Self-propagates via stem plantlets; stem cuttings also root readily in substrate.