Dahlias: the jewels of the late summer garden. Shades of red, yellow, orange, pink, with their petals forming intricate geometric structures. But, like roses and many other flowers, the dahlia spectrum is missing one colour: blue. So why are blue blooms so rare in nature?
11 November is Remembrance Day. As the flowers that grew on the battlefields of WWI, poppies are used as the symbol for this day. This graphic takes a look at the chemical compounds behind their colours, as well as some of the useful medical compounds that can be obtained from different types of poppies.