A Parasite in Disguise
The largest single flower on Earth, Rafflesia arnoldii, has no visible leaves, roots, or stem. It is a holoparasite, meaning it lives its entire life cycle inside another organism. Its host is the Tetrastigma vine, a member of the grape family, found in the tropical rainforests of Sumatra and Borneo. For most of its life, Rafflesia exists only as a network of thread-like filaments woven into the vine's tissue, absorbing water and nutrients directly from its host. It has even lost the genetic material for photosynthesis.
The flower's presence is unknown until it is ready to reproduce. A small bud pushes through the host vine's bark and swells over many months, sometimes for more than a year, into a large, cabbage-like head. The record for the largest measured bloom belongs to a specimen found in West Sumatra in 2020, which measured 111 cm (3 feet 7.7 inches) across. These massive flowers can weigh up to 11 kilograms (24 pounds).
Deception and Reproduction
The plant's common name, "corpse flower," comes from the pungent odor of decaying flesh it emits to attract its primary pollinators: carrion flies. The smell comes from sulfur-containing compounds, specifically dimethyl disulfide and dimethyl trisulfide. The flower's mottled, reddish-brown, fleshy petals add to the illusion of rotting meat. Deceived flies, such as those from the genera Lucilia and Sarcophaga, land on the flower expecting a meal or a place to lay their eggs.
Reproduction is a challenge for Rafflesia. The flowers are unisexual, meaning each bloom is either male or female, and both must be open at the same time in close proximity for pollination to occur. A fly must first visit a male flower, getting coated in sticky pollen, and then travel to a female flower. Since the bloom only lasts for about five to seven days before withering, the window for successful pollination is very small. If successful, the female flower produces a berry-like fruit filled with thousands of tiny seeds. The method of seed dispersal is not fully understood, but small mammals like tree shrews are thought to eat the fruit and spread the seeds.
The flower was first documented by western science in 1818 by an expedition party led by Sir Stamford Raffles. The naturalist on the trip, Dr. Joseph Arnold, was the first to find the specimen, guided by a local servant. Botanist Robert Brown later officially named the genus Rafflesia in honor of Raffles and the species arnoldii after Arnold, who died of a fever shortly after the discovery.