This plant is not yet visible in the Garden.
Plants harvest the sun’s energy using the process of photosynthesis, which takes place in the leaves. Dirt on the leaf’s surface can block out sunlight, so dirty leaves are less efficient at making energy.
Nasturtium has leaves covered in tiny clumps of waxy tubes. This wax causes water to form beads and run off: the leaf is extremely good at repelling water. The water picks up dirt on the leaves as it runs off, so the leaves are self-cleaning. This is called the ‘Lotus Effect’, because it was first described in leaves of the Sacred Lotus (Nelumbo nucifera); during warmer months you can see a Sacred Lotus in our glasshouse. Many man-made surfaces take advantage of the Lotus Effect, including self-cleaning tiles, paints, glass and fabrics, coatings to make microwave antennae less susceptible to rain and snow buildup, and surfaces used for dew harvesting.