Plant chemist Phil Stevenson on the isolation and analysis of plant compounds explains the science behind why flowers smell <\/p>
Memory aids for bees<\/a><\/strong> You may also like<\/strong><\/p> Bees remember specific plant odours or colours and shapes associated with recent past experiences of good food reward once they have fed from them a few times. An extraordinary finding at Royal Botanic Gardens, Kew showed that some plants even \u2018drug\u2019 bees. Citrus and coffee flowers have caffeine in their nectar. When this is consumed it improves the bees\u2019 memory for those flower scents \u2013 and the effect can last for days. This means that bees will recognise these flowers more easily and revisit them more frequently and therefore be more efficient pollinators to these plants. So the next time you smell a sweet flower scent \u2013 enjoy it, but remember \u2013 it\u2019s not designed for you.<\/p> Pollination and competition In a highly competitive world these are what advertise the particular nectar and pollen rewards to the specific animals that need to be persuaded to carry the pollen between flowers. So scent that smells sweet to one animal may smell awful to another. There are even some cases where the scent is a complete con and used to lure an animal in – without offering a reward. For example, the Arum<\/a> family contains many species where the flowers smell of rotting flesh<\/a> or dung, which attracts flies thinking they are going to find food.<\/p> But perhaps the masters of deception are bee orchids (Ophrys<\/i> species), which famously resemble female bees but also produce the pheromone of virgin females to make the con more convincing. For bats and moths a particular scent is essential for distinguishing species as they are likely to specialise on only a few species. Typically, these flowers provide a reward for the visit of a legitimate pollinator but being night creatures they rely heavily on scent because visual clues are less profound in the low light levels.<\/p>