Rafflesia: Lifecycle

Ten Things I Like About... Podcast

Summary: Does a unique flower like rafflesia how a unique life cycle? Join Kiersten to find out!

For my hearing impaired listeners, a complete transcript of this podcast follows the show notes on Podbean

Show Notes:

“Most of the world’s largest flowers (genus Rafflesia) are now on the brink of extinction,” by Pastor Malabrigo Jr, Adriane B. Tobias, Joko Witono, Sofi Mursidawati, Agus Susatya, Mat Eunuch Siti-Munirah, Adhityo Wicaksono, Reza Raihandhany, Sarah Edwards, and Chris J. Thorogood. https://doi.org/10.1002/ppp3.10431

Start the Week Podcast: Mysterious Plants. 04 March 2024. https://www.bbc.co.uk/sounds

“Colossal Blossom: Pursuing the peculiar genetics of a parasitic plant,” by Jonathan Shaw. Harvard Magazine. https://www.harvardmagazine.com

Music written and performed by Katherine Camp

Transcript

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Kiersten - This is Ten Things I Like About…a ten minute, ten episode podcast about unknown or misunderstood wildlife.

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Welcome to Ten Things I Like About… I’m Kiersten, your host, and this is a podcast about misunderstood or unknown creatures in nature. Some we’ll find right out side our doors and some are continents away but all are fascinating.

This podcast will focus ten, ten minute episodes on different animals and their amazing characteristics. Please join me on this extraordinary journey, you won’t regret it.

The third thing I like about rafflesia is its life cycle. In the first episode I hinted it at it a bit. Most of its life it is invisible and is a parasitic plant with a specific host plant. Let’s get into the fine details of rafflesia’s life cycle, and strap in listeners because this one is a doozy. When I chose rafflesia as my next unknown creature, I had no idea how how crazy the life cycle was, but my research has blown my mind. Enough anticipation, here we go.

Rafflesia have no roots, no shoots, no stems, and no leaves. Off to a good start when talking about a plant, right? The only thing left is petals and reproductive parts. Well, that’s essentially what rafflesia are made up of.

They spend most of their life hidden within the vines of their host plant. Vines in the genus Tetrastigma are the current host plants to rafflesia. They may be the chosen host due to the fact that they hold a lot of water, as do many vines.

Rafflesia buds pop out of the vines with no warning, or a least with no prior indication that we have seen. The buds pop out from a vine and will grow for months until they are the size of a cabbage, a large cabbage, like a basketball size cabbage. They look like the cabbage, as well. As the bud grows the petals remain wrapped tight like a cabbage.

Most of the buds will be an orange color, since a good majority of rafflesia are a brick red color. When the bud is ready to bloom, five petals will unfold. In the middle of the flower is the floral chamber. Quoting from the Harvard Magazine article by Jonathan Shaw, the central floral chamber is (quote) “orb-shaped, with a circular opening at the top, [it} resembles a planetarium or astronomical observatory with a mottled roof partially opened to the sky.” (End quote). In the largest rafflesia flower, Rafflesia arnoldii, the chamber is big enough that an infant could comfortably take a nap inside.

This is such a poetic and accurate description of the middle of rafflesia. Inside the opening is a disk covered with spikes. It looks like one of those rubber spiky balls that you can get your for dog. They give the inside of the planetarium structure a bit of a medieval torture chamber feel. Scientists have not determined what these structures do for the flower.

The bloom will last about a week. During that week it is trying to attract pollinators to help is reproduce, just like all flowering plants. Those of you that are gardeners about there, you know exactly what I’m talking about. When the plants that you’ve loving planted and taken care of bloom, then you see the real reward. Pollinators such as honeybees, native bees, butterflies, moths, hummingbirds, and bats are attracted to the blooms and help the plant swap pollen which leads to reproduction. That is the same goal for rafflesia, as well.

They use scent, jut like other flowers, to attract pollinators, but the scent they produce is a bit different than your typical flower. Rafflesia arnoldii, is also know are the ‘corpse lily’ or the ‘carrion flower’. That probably tells you what you need to now about the scent of this enormous flower. It smells like rotting meat. We are going to delve deeper into the details of this odoriferous scent in a future episode, but rafflesia is targeting a specific pollinator, carrion flies.

Carrion flies are attracted to rotting meat where they their eggs so the larvae can consume the decaying flesh and transform into adult flies. Rafflesia employ a trick that many plants use to get what they need from mobile animals, pollen from another flower that they themselves cannot reach. The pollinator will visit the flower that is advertising what it is interested in, take a little reward, unknowingly get itself covered in pollen, then they visit another flower where the pollen from the first flower mixes with the second flower, and so on.

The carrion fly is attracted to rafflesia where they will lay their eggs. They don’t known that this will not help them spread their genetics because when their eggs hatch the maggots will have nothing to consume, but the flower is getting what it wants out of this relationship. When the fly crawls around inside the central floral chamber looking for the best place to lay eggs, they get covered in pollen.

Once again rafflesia is different from other flowers. Most plant pollen is powdery, dusting anything that touches it with a layer of pollen that clings long enough to travel to another flower nearby. Rafflesia pollen is a viscous liquid. The fly’s back gets coated with this thick, yellow liquid where it can remain for several days to weeks. Scientists are not completely sure why rafflesia use a gooey liquid pollen as opposed to a powdery pollen, but it may help keep the pollen in place longer than the powder based pollen.

Rafflesia blooms unpredictably and generally not in clusters. So a pollinator has to travel a lot further to find another rafflesia flower that is in bloom. If the pollen falls off before it finds a second flower, it’s not helpful.

If a rafflesia is successfully pollinated, the female flowers produce fruit that looks like a pile of cow manure. Yum! These piles are filled with hundreds of thousands of seeds. Each of these one millimeter seeds come equipped with an oil body that may have something to do with seed dispersal. Here is where we lose the path of rafflesia life cycle. Researchers have not yet determined how rafflesia seeds get where they need to go to begin life.

We’ve come almost full circle, so let’s go back to the beginning for a moment. Remember when I said that rafflesia is invisible for most of its life until it begins to bud? This is because rafflesias are parasitic plants that rely on a physical connection the a vine in genus Tetrastigma. These vines hold a lot of moisture which may be why rafflesia have chosen these particular vines as a host. To create new flowers the seeds of rafflesia must come in contact with a Tertasigma vine. We don’t know how that happens. Some say that tree shrews may eat them and them poop them out, elephants step on the fruit and track them through the forest to the correct vine, but the oily bodies on the seeds indicate that ants may be the transporters of the seeds. Other species of flowers use oil bodies to attract ants to do their seed dispersal, so this may be what’s happening with rafflesia, as well.

We have successfully come full circle with the life cycle of rafflesia, and I told you it was a doozy. I hope you enjoyed the ride because my third favorite thing about rafflesia is their life cycle.

If you're enjoying this podcast please recommend me to friends and family and take a moment to give me a rating on whatever platform your listening. It will help me reach more listeners and give the animals I talk about an even better chance at change.

So join me next week for another episode about Rafflesia.

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This has been an episode of Ten Things I like About with Kiersten and Company. Original music written and performed by Katherine Camp, piano extraordinaire.