World's smelliest flower opens

It is the first time the flower, Amorphophallus titanum or Titan Arum, has bloomed outdoors in cultivation.

"It smells like a dead person," said one of the crowd. "I happen to be a nurse and that is exactly what it smells like."

The flower started to bloom at the Huntington Botanical Gardens, San Marino, California, at 1630 local time on Monday. The flower reached full bloom by midnight and Brendan Craughwell, a Conservation Assistant, then e-mailed digital images to BBC News Online.

The seed of an idea

Mr Craughwell also revealed a unique self-pollination experiment which was carried out, to try and create seeds.

"First you need to understand how the flower reproduces. The flower tries to mimic a rotting corpse so that it can attract sweat flies, which lay their eggs in dead flesh.

"When the flower first opens, only the female parts are sexually receptive. This period lasts for one to two days. Only after the female parts are no longer receptive do the male parts, called anthers, release pollen. This mechanism prevents self-fertilisation in the wild."

However, when the flower is cultivated in gardens away from its native Sumatra, there is frequently only a single plant. This means self-fertilisation is the only way seeds can be produced.

The Huntington team therefore removed the anthers as soon as the flower opened and exposed them to the gas ethylene.

This was done by sealing them in a bag with rotting apples for a few hours and stimulated early maturation of the anthers and release of the pollen.

The pollen was then placed on the still-receptive female parts. How successful the experiment has been will not be known for at least a few weeks.

Given the smell, it is perhaps fortunate that the flower only lasts for a short time. About 36 hours after it opened, the flower will start to collapse.