Chlorophyll makes plants look green, carotene makes them look red or orange, and xanthophyll makes them look yellow. Plants make fruits and flowers look blue by shifting acidity levels, adding ...

Trochetia boutoniana shows off dark red nectar against a blue background and Trochetia blackburniana produces yellow nectar, which it shows off at the center of a yellow flower.

Bees cannot see red, but they can see blue and green, as well as ultraviolet light. This means colours look very different to what we see, and they can see things we cannot see.

Yellow roses in Germany can hint at adultery. In the US, they simply mean ‘I miss you’. Adam Jacot de Boinod has a lot more. In this week’s Capital Letters.