What Makes This Massive Blossom Smell So Bad?

Today’s post is by Cheryl Hogue, a senior correspondent at C&EN who loves to botanize. She won third place at her county fair for a scary-looking succulent she grew on a windowsill.

Something was making a stink on Capitol Hill this week and it wasn’t Congress.

Corpse flower: Because not everything pretty can smell good.

Corpse flower: Because not every pretty flower can be fragrant. This one smells like dead flesh, then dead fish.  Credit: Cheryl Hogue

The malodorous scent wafted from the titan arum blooming in the U.S. Botanic Garden on the grounds of the U.S. Capitol. This plant, Amorphophallus titanum, also known as the corpse flower or stinky plant, has the largest unbranched flower stem (or in botanist-speak “inflorescence”) on Earth.

I jumped at the chance to have a wondrous and slightly gross experience with this plant, a native of the jungles of Sumatra that rarely blooms.  Yesterday, I queued up in a line that snaked around the exterior of the botanic garden’s glass-enclosed conservatory.  The oppressive District of Columbia heat and humidity failed to deter anyone waiting from their quest to view—and, with hope, to sniff—the stinky plant.

After 20 minutes in line, I entered the conservatory and beheld the titan arum at the peak of its splendor. I was suitably impressed at the yellowish, club-like spadix—the central part that holds tiny female and male flowers—surrounded by the shawl-like maroon spathe.  The bloom is over 5 feet tall.

But alas! There was no smell. Well, I did catch a brief whiff of something that smelled like a food dumpster that had baked in the July sun all day—but that might have been an actual dumpster. A botanic garden volunteer explained to me that the titan arum off-gasses its putrid odor at night, attracting beetles and other pollinators.

What makes the corpse flower smell so nasty? A decade ago, chemists interviewed by C&EN had good hypotheses but hadn’t come up with definitive answers.  In 2010, a group of researchers in Japan clinched the analysis, determining that dimethyl trisulfide was the main chemical that accounted for the titan arum’s stink, which they described as the “rotting animal-like odor” (Biosci. Biotechnol. Biochem., DOI: 10.1271/bbb.100692).

Dimethyl trisulfide, the researchers reported, is among the volatile compounds in cooked onions, cabbage, decayed meats, and, interestingly enough, ulcerating lesions with dead tissue that are associated with some cancers in humans.

Dimethyl trisulfide: Because not every symmetrical molecule can smell nice. This one has a "rotting animal-like odor."

Dimethyl trisulfide: Because not every symmetrical molecule can be aromatic. This one has a “rotting animal-like odor.”

Other compounds contributing to the titan arum’s bouquet are methyl thiolacetate, 3-methyl butanal, acetic acid, and isovaleric acid, according to the 2010 analyses.  The researchers also reported that at the end of the 24- to 48-hour blooming time, the plant’s funk changed to a rotten fish smell. Trimethylamine is the compound responsible for this scent, they found.

No matter how awful this buffet of chemicals smells, I bet botanic gardens could sell tickets for nighttime visits to a blooming stinky plant.  Botany enthusiasts like me want to get a schnoz-full.

 

Author: Sophia Cai

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2 Comments

  1. Oh man, this is so cool. From 100+ miles away it is a lovely-seeming plant, though I am rather curious about the smell. Thanks for serving up the chemistry!