Ah, nasturtiums… beloved of schoolchildren (and gardeners) for how readily they grow and propagate, beloved of cooks for the peppery kick of the edible leaves and seeds, and the splash of colour the flowers bring to salads. I love them for all these reasons, but most of all for the characteristic shapeliness of the flowers: the weirdly beardy fringe on three of the five petals and the elongated nectar spur at the back.