Red flowers use chemical warfare to protect themselves

A new study has determined that an Australian native plant is using chemical warfare to prevent its bright red flowers from being eaten, by using some quantity of cyanide.

According to a report by ABC News, the finding challenges conventional thought that flowers evolved as a way for plants to attract birds and animals that help them cross-pollinate.

The study was done by Professor Byron Lamont and his colleagues from the Centre for Ecosystem Diversity and Dynamics at Curtin University of Technology in Western Australia.

Lamont said that the team studied 51 species of Hakea, and found they could be easily divided into two groupings.

Insect-pollinated species have predominantly tiny, white flowers surrounded by spiky, dense foliage, which they suggest stops animals such as emus and cockatoos from eating the flower.

Bird-pollinated species instead have soft open leaves and bright, easily accessible, usually red, flowers with room for birds to land on stems.

This makes the plant vulnerable to being eaten by emus and cockatoos.

Lamont and colleagues travelled to the heathlands north and south of Perth to collect samples of Hakea.

They macerated the flowers on-site and then used an enzyme and a strip of paper that was sensitive to cyanide to test for its presence.

He said that they found that plants with red flowers contain 10 milligrams of cyanide per gram, enough to make an animal sick.

According to co-author Dr Mick Hanley, of the University of Plymouth, animals that eat the red Hakea flowers may learn to associate the colour with the bitter taste produced by the cyanide.

“The colour red acts as a warning to large vertebrate herbivores like emus, parrots and kangaroos that the flower contains distasteful or even poisonous cyanogenic compounds,” he said.

“It seems that Western Australian plants have not only developed a remarkable defence against would-be flower predators, but that they also clearly advertise the fact,” he added.