Brazilian pennywort: the round-leaved climber

Where it comes from

Hydrocotyle leucocephala grows along the wet margins of streams and ponds across Central and South America, scrambling over mud and water alike. It is an amphibious plant, as happy submersed as it is creeping emersed at the water's edge.

What to expect

Its trademark is the round, coin-shaped leaf held out on a thin stalk. Left to grow, the fast, brittle stems will climb toward the light, break the surface, or drift as a floating tangle — giving you a versatile plant you can train as a midground bush, a background screen or surface cover.

How to keep it

Pennywort is genuinely easy: no CO2, undemanding on water chemistry, and fast enough to strip nitrate and shade out algae. Its only real need is light — in a dim tank the stems stretch and the leaves shrink and space out.

Parameter	Value
Lighting	Medium to high — leggy and sparse in low light
CO2	Not required
Temperature	20–28 °C
pH	6.0–7.8
Hardness	Soft to hard
Fertiliser	Beneficial; a light water-column feeder
Substrate	Any, or none — floats
Growth rate	Fast
Placement	Midground, Background or floating
Difficulty	Easy

Where it works and how to spread it

Plant a few stems in the substrate, wedge them by hardscape to climb, or simply let a portion float. Propagation is trivial: cut any stem into pieces and each grows on. Because it grows so fast, expect to trim weekly to keep it tidy.

What goes wrong

The usual complaint is leggy, bare growth — too little light. Brittle stems also shed pieces that root elsewhere, so it can spread more than you intend; just pull the strays. Otherwise it is one of the hardest plants to actually kill.

More plants in this series

• Water wisteria (Hygrophila difformis) — the shape-shifting stem plant
• Hygrophila polysperma — the ultra-reliable beginner stem
• Guppy grass (Najas guadalupensis) — floating fry cover and nutrient sponge