March 21, 2012 | 6
I woke up, bleary-eyed, to news that would change my week: A corpse plant was about to bloom at Cornell University. In other words, the most amazing thing I could imagine was unfolding, literally, down the street from my house.
The corpse plant has the largest unbranched blossom in the world. Imagine a calla lily, but one that is ten feet tall, three feet wide, and smells like a rotting animal.
Amorphophallus titanum, endemic to Sumatran equatorial rainforests, is prized by botanical conservatories across the world. I first learned about the rare plant eight years ago in a dimly lit taxonomy lecture. It hooked me, and I’ve been studying plant ecology ever since.
I determined to visit this strange specimen every day until it set seed. To get a bit closer to something I thought I would never see.
It looks like a French bread sticking out of a fleshy green vase. Its Latin name is Amorphophallus titanum, or “misshapen giant phallus.” But those who don’t like to offend their audiences, like naturalist David Attenborough, or Cornell University, call the plant “Titan arum.”
The French bread is the spadix, a spike that will soon bear sets of tiny female and male flowers. The spadix is wrapped by a spathe, a modified leaf that looks like one leathery petal. When the corpse plant blooms, the spathe will unfold to reveal its frilled and shockingly purple inner side. This is the event I am impatiently waiting to see.
Next to the blooming corpse plant, in another pot, sits a single, giant leaf with a polka-dotted petiole. This is the vegetative state of the corpse plant, which only flowers every 2-3 years in natural conditions, and in greenhouses even less frequently. This leaf collects energy until the plant’s tuber has enough oomph to flower. Carol Bader, greenhouse manager, has been caring for the two Amorphophallus plants since they were delivered as small seeds ten years ago.
Monica Carvalho, graduate student and official corpse plant guardian, tells me that the plant has shot up over a foot in the past week. She expects it will bloom on Sunday.
It seems the spathe has pulled away, ever so slightly, from the spadix. But perhaps this is wishful thinking. Soon it should smell.
Amorphophallus titanum reeks when it’s blooming, and it attracts flies. Its blossom is purple with darkened orifices, and it matches the sulfurous smell and high temperature of a decomposing carcass. The high temperature (close to 100° F) may help to disperse the corpse plant’s odors across long distances – an important ability for a rare plant that can’t self-pollinate.
Such carrion mimicry has evolved in at least ten plant lineages. And rotting flesh is not the only foul smell a flower can produce: other plants mimic dung, urine, fungi, and fish. The succulent Orbea semota ssp. orientalis produces the compound p-cresol to smell of poop. Somehow the prospect of the corpse plant’s malodor is part of its appeal. Another day of waiting.
Cornell University has set up a webcam on the corpse plant. I keep it open in my browser. Ithaca is a small town, and friends’ faces appear over and over again. I am not the only one excited by the impending bloom.
The webcam heightens the suspense. I am worried that if I forget to reload the page, I will miss something. I am scheduled to visit the plant at 4 pm. The spathe is still wrapped around the spadix. It does not look like it will bloom today. But what business do I have, really, extending my intuitions about Northeastern plants to this otherworldly specimen?
It really is a big blossom. Blossoms exhibit over 1000-fold variation in size, ranging from less than 0.03 inches to nearly three feet in diameter. Giant flowers are rare, but they’ve evolved independently in multiple plant families. One might expect large flowers to be associated with large pollinators, but gigantism appears to be most common to plants pollinated by small beetles or carrion-flies.
When gigantism does evolve, it seems to do so quickly. One study suggests that the big-flowered family Rafflesiaceae is actually derived from a tiny-flowered family, Euphorbiaceae. The largest subgroup of the family, Rafflesia, which includes three foot wide blood-red flowers, experienced a rapid and recent burst of speciation within the last 1-2 million years. One species, Rafflesia arnoldii, increased its flower diameter 73-fold and now bears a 15 lb. bloom.
While many studies contend that increased floral size in species with normal-sized flowers leads to increased fitness, there are few natural history and experimental data on rare, large flowers. It does seem, though, that a disproportionate number of fly pollinated species have giant blooms. Flies are known to prefer larger carrion, which provide better sites to lay eggs, and so perhaps they prefer larger carrion mimics, too. But this corpse plant will be pollinated by graduate students, not flies.
It’s open. It opened late last night, in my sleep.
I visit the corpse plant at 9 am to beat the crowd – over 2,000 visitors so far. The bloom is always a spectacle. The first botanical account of one, in 1878, was dismissed as a fraud until a specimen bloomed at the Royal Botanic Gardens at Kew in 1889. In 1926, when it flowered next, the crowds were so large that police had to control them.
The smell hits me as I walked into the room. I am surprised: it smells more like wet socks than carrion. It is a swampy smell.
Monica Carvalho is pollinating the corpse plant. I watch as the receptive and sticky female flowers are paintbrushed with pollen collected two years ago from another university’s Amorphophallus specimen. Air pumps dangle into the cup of the spathe – researchers are recording volatile emissions before, during, and after bloom.
After fifteen minutes of staring in silent reverence, I am shuffled out of the way by an old lady with a giant camera. More and more visitors are piling in to watch the pollinating. I turn around for one last look into the greenhouse. As I do a young boy, maybe eight years old, walks into the room. He looks over to his left, and shouts to his mother, “Whoaaa – a giant cactus!” And indeed, there is a beautiful cactus in the back of the room. I hadn’t noticed it. Nor had any of the other fifty adults crowded around the corpse plant. This is the nature of spectacle.
I visit the bloom again. This time without the edge of expectation. The greenhouse is less crowded. In another day or two the spathe will collapse, unceremoniously. The pollinated flowers will ripen into bright red fruits. These fruits will be shipped off to other research institutions.
On my walk home I notice that skunk cabbage, Symplocarpus foetidus, is in bloom. It’s of the same family as the corpse plant. An early spring bloomer, it can maintain a temperature in its spadix of around 68° F even when the ambient air temperature drops below freezing. And in fact, just like the corpse plant its pungent odor and deep red hue attract fly pollinators.
Possibly what makes the corpse plant so different from the skunk cabbage is not its size, but a more intangible ability to attract admirers – crowds of humans with notebooks, cameras, and tiny paintbrushes. I bend down to visit the skunk cabbage.