The corpse flower lives up to its nickname. Native to Sumatran rainforests of Indonesia, the giant tropical plant can live for decades and grow over 12 feet tall, but its most famous for the deathlike scent it emits while blooming. And while titan arum’s rotten meat aroma is undeniable to anyone standing close to it, experts have long been at a loss for how it chemically generates the smell. But the molecular mystery is now reportedly solved thanks to new research from a team at Dartmouth. According to their study published on November 4th in PNAS Nexus, the corpse flower’s stench primarily stems from an organic compound, combined with a biological process typically only found in animals.
A titan arum doesn’t flower annually, and instead undergoes a short blooming cycle once every five to seven years. Over just a few days, a frilled, dark red petal layer opens at the base of the plant’s large central stalk. The corpse flower also technically isn’t singular, and instead contains multiple smaller flowers inside this stalk, also known as a spadix. Once exposed to potential pollinators, the titan arum’s spadix then begins to warm up as much as 20 degrees Fahrenheit higher than the ambient temperature around it in a process called thermogenesis. Only then does the corpse flower begin to give off its sulfurous chemicals meant to attract flies and other insects.
Thermogenesis is common in animals thanks to uncoupling proteins, which block the storage of chemical energy to reroute it as heat. But thermogenesis is extremely rare in plants, and botanists were at a loss as to what initiated it in corpse flowers. Dartmouth’s own 21-year-old titan arum, nicknamed Morphy, last bloomed in 2016 and 2022. Both times, researchers led by biological sciences professor G. Eric Schaller collected tissue and leaf samples that they then used for RNA sequence analysis.
[Related: Corpse flowers across the country are swapping pollen to stay stinky.]
“This helps us see what genes are being expressed and to see which ones are specifically active when the appendix heats up and sends out odor,” he explained in a Dartmouth profile on November 8th.
Schaller and collaborators then identified what kicks off the corpse flower’s thermogenesis, as well as the specific chemical culprits behind its smell. RNA analysis detected the presence of enzymes called alternative oxidases that grew in number during Morphy’s flowering, as well as genes necessary in the metabolization and transport of sulfur.
With help from researchers at the University of Missouri, the team then used mass spectrometry to measure the corpse flower’s amino acid contents. In particular, researchers noted high levels of methionine that underlie compounds responsible for foul-smelling odors. While this was previously predicted by Schaller’s team, they also discovered the active enzymes that make putrescine—the compound found in the odors emitted by rotting animals.
Taken all together, the discoveries may not do much to mitigate the corpse flower’s awful smell, but at least experts can now pinpoint how titan arum generates such impressively bad aromas. Moving forward, Schaller hopes to learn what initiates a corpse flower’s bloom cycle, as well as if multiple plants synchronize their schedules to increase the chances of pollination.