What is the Largest Flower in the World?

The world's largest flower is one which doesn't have any visible roots, stems or leaves, despite being a type of vascular plant. The reason is because the world's largest flower is a parasite. Also known as the giant padma, the corpse flower (Rafflesia arnoldii) uses the nutrients provided by its host plant to survive. This host plant is the Indian chestnut vine (Tetrastigma leucostaphylum) in West Sumatra.

How big is the world's largest flower?

The corpse flower has an overall diameter of around 3.3 ft (1 meter) once it has bloomed. Each flower has five petals which emerge from a single bud. These bus look a little like cabbages before they bloom. The record for the largest Rafflesia arnoldii is 3.9 ft (1.2 m) diameter and a weight of 24 lb (11 kg). While it can take five years for the flower to bloom, this bloom only lasts around 1 day before it starts to decay.

In addition to being the biggest flower in the world, the corpse flower has other unique characteristics. Known as a type of carrion flower, it mimics both the sight and smell of a dead animal. This is thanks to its red petals which are covered in warty protuberances and structures which resemble hairs and teeth. The smell it emits is deathly, the reason it is commonly known as the corpse flower.

The reason for this resemblance to carrion is so that it can be fertilized by flies. Rather than other types of pollinator such as bees, these flies are not attracted by nectar. They believe the corpse flower is a dead animal on which they would normally feed. When they visit the flower, they are covered in pollen which they transfer to another corpse flower plant

Although it has not been officially listed as endangered, it has been observed that there are fewer and fewer rafflesias. This is due to factors such as deforestation and tourism in its native countries of Borneo and Sumatra, which interferes with its development.

While the corpse flower may have the largest individual flower in the world, there many plants which are much larger in total size. Learn more with our article explaining the difference between gymnosperms and angiosperms.

There may be some confusion between Amorphophallus titanum and Rafflesia arnoldii. This is because both are commonly known as the corpse flower. They are both carrion flowers which mimic the smell of dead animals to attract pollinators. In addition to the putrid smell reminiscent of decomposing animal tissue, the titan arum also produces heat to attract pollinators.

Another point of confusion is the size of their inflorescence. If you look at the titan arum, it appears as if it has a large flower which is even bigger than the corpse flower. What you will see is actually an inflorescence of many flowers. While Rafflesia arnoldii has the largest individual flower in the world, Amorphophallus titanum has the largest infloresence of any flowering plant.

The flower is called an inflorescence because it is composed of multiple small flowers. The macro structure we see is a spadix, a column containing the female and male flowers. It is surrounded by a spathe, the equivalent of a petal cover. This is green at the base before turning white and ending in wine red. Before blooming, a tree-like leaf grows. It re-emerges again and again until the underground bulb has enough energy to produce the inflorescence.

The titan arum blooms around three times in each lifespan, doing so spontaneously and unpredictably. Beneath the soil is a tuber that stores liquids and nutrients. It grows only in the jungles of Sumatra. It is currently in danger of extinction due to habitat loss, but can be found in some botanical gardens with special collections.

Another of the world's largest flowers is the pelican flower (Aristolochia grandiflora). This flower is also a type of carrion flower. The largest flower in Central America, it measures 2.2-2.6 ft (70-80 cm) in diameter. It has a peculiar appearance as it is shaped like a flat heart with an opening at the front. This is the space which houses the pollination tube. They are white with many reddish-brown veins, extending to the center of the tube.

While the pollination parts are found in this cavity, there is a long extension at the top which makes it such a large flower. The coloration of the pelican flower mimics carrion, as does the smell of rotten meat it emits. Flies enter the flower's opening and are trapped by hairs inside the tube, preventing them from escaping for 24 hours. During this time the plant transfers pollen and gives them nectar. After a while, the hairs retract and allow the fly to escape to pollinate another pelican flower.

Discover more about how the anatomy of flowers affords it the ability to pollinate with our article asking what is the perianth of a flower?

A plant native to arid South African climates, this big flower is not a type of carrion plant. Like the titan arum, the king protea (Protea cynaroides) is not actually one big flower, but a plant with a large inflorescence. This inflorescence measures around 12" (30 cm) in diameter. Also known as the king sugar bush or honeypot, it has nectar which provides a deliciously sweet meal for various pollinators.

The outside of the king protea has rigid bracts which are velvety to the touch and pink in color. They somewhat resemble the bracts of globe artichoke. The flowers are located inside and which appear as white or yellow filaments. There are man-made cultivars that present in different shades of pink, with some even appearing purple or red.

It's a very hardy flower that tolerates drought, high temperatures, frost, rain and even fire. It can be grown as a cut flower for floral arrangements or planted in gardens.

Learn more about fire-resistant plants with our article on types of pyrophytic plants.

As we have seen, some of the world's largest plants are found in the deepest darkest jungles of remote climes. The Russian mammoth sunflower (Helianthus annuus) is a plant which is much more common to Europe and the US. These plants are a cultivar of the sunflower plant that established in Russia to enhance certain characteristics, specifically its dimensions. Each head measures around 12" (30 cm) in diameter and can reach up to 13 ft (4 m) in height.

Like some of the others in this article, it is not one big flower, but a very large inflorescence. It is one the most popular sunflower cultivars, often sold as a cut flower for striking bouquets. It can also be grown as a living fence plant that separates spaces, useful for garden design.

While they may not be the largest flowers in the world, you can discover some of the plants with big flowers which you can keep in your home or garden.

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