When it comes to the biggest flower in the world, there isn't quite so clear cut an answer as you might imagine. Technically speaking it's simple, but when it comes to the impression one gets and sheer awe, not so much. There are three contenders, but one of them is on a boring palm tree and looks impressive, but not much more. Let's confine ourselves to the other two.
The first is the Rafflesia from southeastern Asia. There are several species, all quite similar to each other and with similar ways of living. They're really rather perculiar, they have no stem, no leaves and no proper roots, they are in fact, parasitic. They grow into their host plant with what's called a 'haustorium', much like fungi, toadstools and the like, stealing all their food from another's hard work with its thready network. You can't really see them at all until it flowers, the buds having developed for several months, but once they do... Wow!
The smallest of them is about 12 centimetres (5 in) across but the crown for biggest single flower in the world goes to Rafflesia arnoldii, reaching a whopping 1 metre diameter! Must be a wonderful feast for the senses, right? The delicate beauty, the sensual aroma. Not really, no. The petals are thick and fleshy with a blotchy red and orange colour. It looks a bit like rotting flesh, which is apt because it smells like rotten flesh, which attracts hordes of pollinating flies who were looking for rotting flesh and may well have just finished off a few lumps of rotting flesh before they got here. No wonder it's often called the corpse flower. Oh well.
It's probably still unfortunate that they are quite rare and are seldom seen. They only grow on a particular genus of vine that is found only in undisturbed rainforest, it steals all that nourishment to grow a flower that blossoms for only a few days and each flower is either male or female, so pollination is even rarer than the flower itself. No wonder no-one is quite sure how they get their seeds around.
Let us move on to the other contender, and in case you're hoping for something that will spread the scents of Spring far and wide, bringing love and joy to all, I should warn you that it also gets called a corpse flower. A bit confusing that, so Sir David Attenborough came to us and led us out of confusion and into tranquilty, as he so often does, by christening it the Titan Arum. You've probably seen its more humble relatives, a central spike is covered in a cluster of tiny flowers with a single colourful petal surrounding it. Arums must feature in the vast majority of tropical flower bouquets all over the world.
The difference with the titan is that the central spike, or spadix, gets to some 8 or 9 feet tall with a 10 foot circumference! A suitably gigantic 'petal', or spathe, surrounds it, a dark, brooding burgandy on the inside, an alien world green on the outside. When in bloom, the spadix reaches human body temperature and helps spread the scents of death and decay far and wide, bringing fear and nausea to all, but mainly attracting insects with indicitive names like 'carrion beetle' and 'flesh fly'.
When the flower dies back the titan arum makes its presense felt with a single leaf, 6 metres (20 feet) tall and 5 metres (16 feet) across, that splits up into smaller leaflets and dies and regrows every year. All this is to gather enough energy to flower once more, which it may not do for several years. Another difference from the Rafflesia is that the titan has both male and female flowers that open a couple days after each other on the same spadix, providing more possibility for pollination.
One similarity though, is that they are both found in the rainforests of the Indonesian island of Sumatra. Perhaps there's something in the rain?