The flowers are produced in cymes of 8–20 together, each flower with a pure white to pale purple five-lobed calyx 2.5 cm in diameter, and a red five-lobed corolla 2 cm long and in diameter.

With a minimum temperature of 10–13 °C (50–55 °F), in temperate areas it requires shelter and a frost-free environment.

[3] This plant has gained the Royal Horticultural Society's Award of Garden Merit[4] (confirmed 2017).

William Cooper Thomson (1829-22 March 1878), a missionary and physician in Nigeria, in honor of his late first wife.

Specifically, its root system must be partially submerged in water most of the time, and it wants very good light.