The colour red
Plants cannot walk. Unable to drift down to the local café, attend this evening's book launch or gate-crash a party, flowers have had to resort to other ways of connecting. True, their roots may wander and branches may wave, but really what appears above ground level is pretty moored. Yet that is where their reproductive organs are, which need to meet so that the plant's pollen can be fertilized. This is achieved indirectly by using animal pollinators - whose attention, however, needs to be grabbed. Nectar fulfils this role wonderfully. A sweet liquid secreted by flowers, nectar is concocted to tempt insects or vertebrates whose bodies, as they feed off it, may inadvertently pick up pollen in one flower and deposit it, in all innocence, on another flower's stigma. So as not to be missed, a little like waving a flag, a flower's nectar may occasionally be brightly coloured: yellow, deep purple, blue, green, red or even black. In this light, the striking red nectar of Nesocodon mauritianus, a blue flower endemic to the island of Mauritius, seems to have evolved to attract a day gecko and is synthesized thanks to the close collaboration of three enzymes: Nec1, Nec2 and Nec3.
