It is a fast-growing plant, with trailing stems growing to 0.9–1.8 m (3–6 ft). The leaves are large, nearly circular, 3 to 15 cm (1 to 6 in) in diameter, green to glaucous green above, paler below; they are peltate, with the 5–30 cm long petiole near the middle of the leaf, with several veins radiating to the smoothly rounded or slightly lobed margin.

Lotus effect

Nasturtium leaves, like some other species, demonstrate the lotus effect, whereby rainwater falling on the surface gathers into globular droplets which roll off the leaf, leaving it dry and clean.

Flowers and fruit

The flowers are 2.5–6 cm in diameter, mildly scented, with five petals, eight stamens, and a 2.5–3 cm long nectar spur at the rear; they vary from yellow to orange to red, frilled and often darker at the base of the petals. The fruit is 2 cm broad, three-segmented, each segment with a single large seed 1–1.5 cm long.

The Elizabeth Linnaeus phenomenon

Das Elisabeth Linné-Phänomen, or the Elizabeth Linnæus Phenomenon, is the name given to the phenomenon of "flashing flowers". Especially at dusk, the orange flowers may appear to emit small "flashes". Once believed to be an electrical phenomenon, it is today thought to be an optical reaction in the human eye caused by the contrast between the orange flowers and the surrounding green. The phenomenon is named after Elisabeth Christina von Linné, one of Carl Linnaeus's daughters, who discovered it at age 19.