The Stench of Death, brought to you by the Forests of Sumatra

(Via: The Parasitic Plant Connection)

Common Name: Giant Rafflesia

A.K.A.: Rafflesia arnoldii

Vital Stats:

  • One of about 28 species of Rafflesia, all parasites native to southeast Asia
  • Dioecious: produces male and female flowers on separate plants
  • Flowers last only a few days

Found: In the rainforests of Sumatra, Western Indonesia

It Does What?!

In my very first post here on Questionable Evolution, I discussed the Titan Arum, a.k.a. Corpse Plant, known for its pungent aroma and generally phallic appearance. This rare oddity is confined to the ever-shrinking rainforests of the western Indonesian island of Sumatra. Now meet its neighbour and fellow rotting flesh imitator, the Giant Rafflesia. Like the Titan Arum, this species is found only in the Sumatran rainforest and uses its odour to attract carrion flies for pollination. (With all the plants pretending to be dead animals on this island, it’s a wonder the flies ever actually find themselves any real carcasses.)

How big?  THAT big.
(With Mr. Troy Davis, Via: The Parasitic Plant Connection)

Rafflesia’s claim to fame in the plant world is that it produces the largest flower on Earth. A single bloom from Rafflesia arnoldii can reach a diameter of 1m (3.3’) and a mass of up to 7kg (15lbs.). In other words, one flower weighs about as much as your overweight cat. Impressive, sure, but what’s more interesting about this plant is that the flower’s the only part of it you’re ever likely to see.

Much like dodder, rafflesia is a holoparasite, depending entirely on a host plant (in this case, a vine of genus Tetrastigma, part of the grape family) for its water and nutrients. Unlike dodder, however, rafflesia doesn’t grow up and over its victim, eventually smothering it- no, this plant grows inside its host. Over the course of its evolution, the leaves, roots, and stems of rafflesia have been reduced to nothing but miniscule threads that grow, fungus-like, through the intercellular spaces of another plant, absorbing whatever they require. The giant flower arises directly from the roots or stem of the host vine, pushed out through the host’s tissues. Think chestbursters from Alien. Beyond the juvenile phase when a new seedling searches for its host, this is the only part of rafflesia that will ever see the light of day.

Flowering Time!!

Interestingly, botanists have found that rafflesia’s giant flowers evolved over a very short period of time (relatively speaking), with flower diameter increases of, on average, 20cm per million years. Blindingly fast, as plant evolution goes. The reason for this, they speculate, may have been a preference on the part of certain carrion flies to feed on larger animal carcasses. The range of flower sizes seen in different species of genus Rafflesia probably functions to attract different sets of fly species with varying tastes – some want wee little dead mice, some want dead rhinoceros, judging from the size of these things.

Plants: give ‘em a few million years, and they can mimic almost anything.

Says Who?

  • Barkman et al. (2008) Current Biology 18: 1508-1513
  • Beaman et al. (1988) American Journal of Botany 75(8): 1148-1162
  • Patifino et al. (2002) New Phytologist 154: 429-437
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Smells like death, looks like… an Amorphophallus?

Amorphophallus titanum

Common Name(s): Corpse Flower, Titan Arum

A.K.A.: Amorphophallus titanum

Found: Sumatra, Western Indonesia

It Does What?!

Looking like something from an Enterprise away mission, this is a plant you won’t soon forget. For those who imagine that biologists don’t have a sense of humour, the scientific name of the Corpse Flower is Amorphophallus titanum, which is Latin for ‘giant misshapen penis.’ And it’s not a bad description; the plant produces a… well, vaguely penis-shaped bloom that grows up to three feet tall and, as if we needed more to snicker about, produces pulses of heat which move from the base to the tip, reaching temperatures of over 36 degrees Celcius (97 Fahrenheit).

It happens to every Amorphophallus at some point…
(Via: plantae.ca)

It’s actually a bit of a misnomer to call this phallic monstrosity a flower- it’s really an inflorescence, a structure on which smaller, individual flowers grow. In the case of Amorphophallus, that cone in the middle is called a spadix (think calla lilies or jack-in-the-pulpit… same plant family), and holds upwards of 900 tiny flowers, of which about half are male and half are female.

Naturally, all those tiny little flowers need to get pollinated in order to create more giant-penis-plants, and the pollinators of choice for Amorphophallus are carrion beetles and blowflies. How to attract the attention of your favoured pollinators in a busy Sumatran rainforest? You give them what they want – the stench of rotting flesh. Those pulses of heat I mentioned before actually serve a purpose; they work like a convection oven, throwing off a foul odour which rises above the canopy as the warmer air rises. This allows the scent signal to be carried over greater distances. And how bad does it smell? Researchers of the plant note that a principal chemical component of that funk is known to also be the main source of the delicate bouquet that is rotting human flesh. Mmm… For another overly-vivid mental picture, be sure to check out a close relative of the Corpse Flower, Helicodiceros muscivorus, a.k.a. Dead Horse Arum.

Says Who?

  • Barthlott et al. (2009) Plant Biology 11: 499-505.
  • Shirasu et al. (2010) Biosci. Biotechnol. Biochem. 74(12): 2550-2554.