Imagine you are a beetle flying over a rainforest canopy. You are on a mission—seeking out an intoxicating scent that will mark the perfect spot to lay your eggs. Suddenly, you smell it: the unmistakable, irresistible scent of rotting flesh.
Entranced, you descend to this decadent stench. You find your target—it is a strange-looking carcass, but who could deny its allure?
But you—and many beetles, flies, and bees before you—have been duped. The trickster is titan arum; an endangered corpse plant whose deceptive inflorescence has been shaped by evolution to attract pollinators.
One individual of this rare plant bloomed on July 24th at UCR’s Botanic Gardens. Nicknamed “Little Miss Stinky”, this was the plant’s first reproductive event. It will likely not flower again for another few years. Though they bloom for less than 40 hours, each inflorescence is a masterpiece: an immense outer spathe surrounds a columnar spadix that can extend upward up to eight feet.
With infrequent blooming and short-lived flowers, reproductive success is not guaranteed for this species. Additionally, attracting pollinators in the dense vegetation of its native habitat in Sumatra, Indonesia, is no easy task. With low population densities and crowded conditions, Titan arum needs to produce a spectacular flower to attract insect pollinators.
To this end, this plant has evolved a suite of traits to make each gargantuan flowering effort worthwhile in attracting insect pollinators. First, smell. Composed of many compounds, but mainly of disulfide and dimethyl trisulfide, the scent mimics dung and rotting flesh. Scientists are still searching for the main pollinators of titan arum, but it is likely that this scent tantalizes dung beetles and carrion flies who feed and lay their eggs on rotting flesh, and one study confirmed that stingless bees pollinate the plant.
The smell emanates from the central spadix, the male and female flowers, and the spathe; and is spread by the plant’s second pollinator-attracting trait: heat. The spadix heats to 16°F above ambient temperature, volatilizing its smelly compounds.
Once an insect arrives, it slides into the base of the meat-red spathe and is coated with pollen from the male flowers located at the base of the spadix, just above the female flowers. Once the insect leaves it is deceived by another titan arum, depositing pollen onto its female flowers. Since male and female flowers in an individual plant do not open synchronously, cross-pollination is the norm. Seeds form, and the titan arum’s deception has succeeded.
A reproductive strategy that is adaptive for species at low population densities or that flower infrequently does not assure success in our changing world. Scientists estimate that only 1,000 individuals of titan arum exist in the wild, and its numbers are dwindling. Habitat loss driven by conversion for agriculture, illegal logging, and human population growth put the species in danger of extinction.
Organizations like the Chicago Botanic Garden and a network of botanic gardens, including UCR’s, are working to conserve this species by creating banks holding its precious genetic information. It is my hope, and the hope of our stench-seeking insect friends, that these groups continue their work to conserve the Titan arum so the world can remain a more interesting—if not more stinky—place.
About the author:
Annika Rose-Person is a PhD candidate in Dr. Nicole Rafferty’s lab in the department of Evolution, Ecology, and Organismal Biology. She studies the effects of climate change on plant-pollinator interactions, focusing on how early snowmelt impacts pollination in the alpine of the Colorado Rocky Mountains and on how drought affects pollinator behavior using native southern California species.
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