Who knew flowers can grow this big?

Two of the greatest of them all: the corpse flower (Rafflesia arnoldii) and titan arum (Amorphophallus titanum). Image credit: Alison Druhan / Shubert Ciencia

Flowering plants are among the most diverse forms of life on Earth, and the ones withe most enormous flowers show just how far the adaptations have gone.

From the three-feet-in-diameter “corpse flower” to a type of magnolia with a flower much bigger than a grown man’s hand, here are five of the biggest flowers on our planet.

Corpse Flower (Rafflesia arnoldii)A corpse flower and a cell phone for scale. Image credit: Antoine Hubert

One of the three national flowers in Indonesia, Rafflesia arnoldii is a member of the monster flower genus and is known for producing the largest individual flower on Earth. Its fully developed flower appears above the ground as a thick fleshy five-lobed structure weighing up to 11 kg (24 pounds) and measuring about one yard (almost one meter) across. The enormous flowers emerge from very large, cabbage-like buds typically measuring 12 inches (30 cm) in diameter, but the largest (and the largest flower bud ever recorded) found at Mount Sago, Sumatra in May 1956 was 17 inches (43 cm) across.

The corpse flower remains open five to seven days, emitting a foul odor that attracts flies and beetles, which are believed to be the pollinating agents.

A fly helping a corpse flower to pollinate. Image credit: Paul Williams

Rafflesia arnoldii is a parasite that can only be seen outside the host plant when it is ready to reproduce, with the enormous flowers being the only part of the plant that are identifiable as distinctly plant-like. It grows only on the tendrils of the Tetrastigma vine, which in turn only grows in pristine rainforest. This means the habitat of the world’s largest flower is rapidly disappearing.

Titan Arum (Amorphophallus titanum)Endemic to the rainforests of western Sumatra, Indonesia, titan arum (Amorphophallus titanum) can grow to be 12 feet (3.65 meters) tall. Image credit: Richard J. Rehman

Bestowing the “largest flower” title is not an easy job, as it’s not only about measuring blooms. Although the gigantic Amorphophallus titanum has the largest unbranched (non-tree growing) inflorescence that can reach over 10 feet in height – so it is by no means small – this huge rainforest gem is not a single flower but is composed of hundreds of small buds growing on the same stalk.

Similarly to Rafflesia arnoldii, it is also called corpse flower due to its odor, which is like that of decaying flesh. A carrion flower, it uses its not-so-pleasant scent to attract various types of flies, bees and other insects for pollination.

The titan arum’s berries are laid out in a regular cylindrical form resembling the packing of spheres inside a cylindrical confinement.

Titan arum berries. Image credit: Glamhag

Native to Sumatra, Indonesia, the plant remains rare there but is now cultivated in gardens around the world. Blooms remain infrequent, however, both in the wild and in captivity.

Sunflower (Helianthus annuus)Look, I have a sunflower tree! Source: Reddit

Everybody knows (and loves) sunflowers, but the fact that they can grow extremely huge is less well-known. Their erect rough-hairy stem typically reaches a height of 10 feet (3 meters), but the tallest sunflower was about three times bigger!

According to giantgardening.com, which tracks records, the tallest sunflower in the world was grown in Germany by Hans-Peter Schiffer back in 2016. That flower stood 30 feet one inch (9.17 meters) tall.

Schiffer is a master of growing monster sunflowers, having previously held the record on two other occasions.

Hans-Peter Schiffer and his family with the record-holding sunflower. Image credit: Hans-Peter Schiffer

But its not only the height of sunflowers that can reach into the extremes, as the flowers themselves can reach a whopping two feet (60 cm) in diameter. The largest sunflower head on record was grown by Emily Martin of Maple Ridge, British Columbia, Canada in September 1983, and it measured 32.25 inches (82 cm).

Lotus (Nelumbo nucifera)The lotus flower can grow as big as 12 inches (30 cm) in diameter. Image credit: lecercle

Having a very wide native distribution ranging from India and Sri Lanka, through northern Indochina and East Asia, to New Guinea and Australia, lotus plants are adapted to grow in the flood plains of slow-moving rivers and delta areas, where an individual plant can drop hundreds of thousands of seeds onto the waterbed every year.

While lotus leaves float on, or are held above, the water’s surface, the flowers usually grow on thick stems rising several centimeters above the leaves. The leaf stalks can reach 6-7 feet (about 200 cm) in length, and the leaves themselves may be as large as 31 inches (80 cm) in diameter. The beautiful flowers can reach as much as 12 inches (30 cm) across, but 14 inches (35 cm) have also frequently been reported. Some cultivated varieties have extraordinary numbers of petals, even up to 5000 – the greatest number recorded for any plant species.

Some varieties can have up to 5000 petals, but this one conquers with its beauty and size. Image credit: T.Voekler

Similarly to humans and other warmblooded animals, the lotus plant has the remarkable ability to regulate the temperature of its flowers to fall within a narrow range. Australian scientists found that lotus flowers blooming in the Adelaide Botanic Gardens maintained a temperature of 86–95 °F (30–35 °C), even with the air temperature dropping to 50 °F (10 °C). They suspect the flowers may be doing this to attract coldblooded insect pollinators.

Magnolia (Magnolioideae)The beautiful (and huge) magnolia flower. Image credit: William (Ned) Friedman

Also having a worldwide distribution, Magnolia is an ancient genus of about 210 to 340 flowering plant species named after French botanist Pierre Magnol (and not because the flowers are so magnificent, or even magnified). Appearing before bees evolved (fossils of plants indentifiably belonging to the Magnoliaceae family date to 95 million years ago), the flowers of Magnolia species are thought to have evolved to encourage pollination by beetles. To avoid damage by the latter, the carpels of Magnolia flowers are extremely tough.

Out of all Magnolia species, Magnolia ‘Atlas’ boasts the biggest flowers, reaching a whopping 14 inches (35 cm) across.

A grown man’s hand is dwarfed by Magnolia atlas. Image credit: Yamina Rare Plants

The blooming beauty of nature at its height – or width, for that matter.