Thu
Nov 18 2010 9:42am
Ringworld 40th Anniversary: A Ringworld Mystery, Why Are Sunflowers on the Ringworld?

Slaver Sunflowers art by Todd HamiltonLarry Niven used his previously created Known Space universe as the backdrop for the Ringworld story. It was a rich backdrop. Included in those previously published stories were Slaver sunflowers, genetically engineered by an alien race called the Tnuctipun. The Tnuctipun were telepathically controlled by the Thrintin (aka Slavers). Both species died off in a rebellion a billion and a half years ago, but a number of the genetically engineered life forms survived into the present day.

Slaver sunflowers are plants with a single silvered blossom that focuses light onto a photosynthetic node in the middle of the flower making food for the plant. The silvered blossoms can concentrate light elsewhere too. Ostensibly, the Tnuctipun genetically engineered sunflowers to protect the boundaries of Slaver estates. Individually, sunflowers wouldn’t give anyone more than a bad sunburn, but a hedge or field of them concentrating sunlight in unison would burn an invader to ash (at least during the day). This makes them very dangerous and, opens up a lot of possibilities because Louis and Speaker discover a huge field of sunflowers on the Ringworld.

The question is, given how dangerous they are, why would anyone bring sunflowers to the Ringworld? There are two possibilities: either the City Builders brought them from another world, or the Ringworld Engineers did. If the City Builders brought them back from one of their interstellar expeditions then they probably got loose when the cities fell. However, if the Ringworld Engineers brought them there is a more interesting possibility.

In order to burn an invader, the sunflowers must have been controlled in some way (to know who to aim at). We know that the Slavers didn’t control the sunflowers so the remaining possibility is the Tnuctipun. In order to control the sunflowers the Tnuctipun must have been able to communicate with them, at least at the field level. This communication probably used the Tnuctipun science language which we know the Tnuctipun built into the Bandersnatchi (another of their engineered life forms). Also, we know from previous Known Space stories that the Tnuctipun liked elegant designs. Their designs served multiple purposes in both their technological and biological constructs.

Do sunflowers potentially have multiple purposes? The answer is yes. Not only can sunflowers destroy objects by focusing sunlight on them, but a field of them would also make an ultra high resolution optical interferometer (a type of telescope). Sunflower fields then, acting as enormous optical interferometers, would be able to collect intelligence on ships and facilities in orbit as well as on other bodies in any given solar system. Therefore, the Tnuctipun probably would have designed sunflowers with both offensive and intelligence gathering capabilities.

We don’t know if the Tnuctipun designed sunflower fields to be sentient. We do know that they would have focused their efforts on image processing, as interferometers require enormous amounts of computer processing. Sentience may have been added in a supervisory role. Or, perhaps sentience developed as an emergent property. In either case one gets an image of an ethereal, almost ghostly, presence as the sunflower mind. If sunflower fields are sentient then different sized fields could have different levels of intelligence. However, the Tnuctipun might have placed limits on the amount of processing power which any individual sunflower field could attain (by limiting root connectivity). They would have done this to address the tendency for AIs in the Known Space universe to go rogue. In any case, whether designed or emergent, sunflower fields could be sentient.

How could individual plants communicate with their neighbors and form the necessary processing networks? Each sunflower might have a bulb with roots extending out from it. The bulb would contain a very small amount of optical neural tissue (probably less neural tissue than a fruit fly) that would control the pointing of the sunflower and provide some limited amount of memory. This bulb would be connected to several nearby sunflower bulbs using optical fibers in the sunflower’s roots. This connective topology would make a sunflower field a massively parallel optical computer. A sunflower would create light used in its optical neural tissue and fiber optic root system by using light emitting molecules which in turn would be powered by sugars (or their analogues).

The sunflowers might lack long term memory. The Tnuctipun would have designed them to process the data they collect but only retain the processed images long term (until the images were accessed by the Tnuctipun). Image collection would occur at night while image processing would be more likely to go on during the day (when the plants are continuously turning sunlight into sugars). For security purposes, the sunflowers would forget most things not hardwired into them. Think of a huge intellect that can’t remember anything for more than a day (or at least not much). Treaties would be difficult to negotiate unless the sunflowers burned their contents into a nearby mountain side (writing in the Tnuctipun science language).

We know that the Slavers couldn’t read the minds of their computers. In addition to having a computer-like mind, the use of optical neural tissue alone might have made the sunflowers immune to the Slavers’ Power. Also, the Slavers typically focused their Power on a single individual mind, not a vast field of plants; a single sunflower would not even nudge the sentience meter (it would be like commanding a single neuron). But, the question remains, why weren’t sunflowers destroyed along with all the other sentient species in the galaxy at the end of the Slaver War? As suggested, sunflowers may have been designed to be immune to the Slavers’ Power. However, even if sunflowers weren’t immune from the Slaver telepathic amplifier that ended all intelligent life in the galaxy, their seeds would still germinate and grow into adults after the suicide command was given.

Sunflowers would be a prime customer for Garvey Limited (“The Handicapped”). Garvey would first sell them permanent memory storage devices. Next, they’d sell them something analogous to Dolphins’ Hands to give them a way to manipulate their environment (probably closer to robots without brains). One way the sunflowers might pay for these devices is by solving math problems or by doing massive simulations.

If the sunflower fields can dynamically reconfigure their networks to add and subtract portions of a field (by connecting or disconnecting root connections) then it would change their intelligence and might change their personality. If that happens, the Known Space definition of Legal Entity (LE) might have to become more dynamic (and perhaps it already is, given that Jotoki can apparently perform an analogous reconfiguration). In their natural state, sunflower fields would probably find it easier to talk to computers than to biological LEs.

Back to the Ringworld and how all this relates to it: Sunflower field sentience would not be discovered until after the Second Ringworld expedition in 2878. Otherwise the expedition would know that sunflower fields are sentient. We know from Ringworld sequels that the Ringworld Engineers created reproductions of nearby worlds with the potential for intelligence, or on which intelligence had arisen, in one of the Great Oceans. If the sunflower fields are sentient, then this explains why the Ringworld Engineers brought them to the Ringworld. They were just another alien race the Engineers wanted to keep an eye on. Then, someone (probably a City Builder) innocently transplanted a few from their island environment, and the sunflowers started taking over the Ringworld (a very slow process).

Even so, sunflowers will never take over the entire structure’s land area. Sunflowers need carbon dioxide to live and this comes from microbes and animals. There are no geological processes on the Ringworld to hold and recycle carbon dioxide, except the Spill Mountains. So, while sunflowers can eventually take over much of the Ringworld they need to let at least microbes survive. This doesn’t mean that there wouldn’t be animals, and that they wouldn’t be sentient. After all, since the sunflowers don’t have any way to maintain the Ringworld, they need to leave some sentients around who can maintain the place.

As you can see, the Ringworld is a fun playground.


Doug McElwain has been a science fiction fan for over forty years. As a fan, he has corresponded with Larry Niven and Ed Lerner about the implications inherent in the Fleet of Worlds, Ringworld, and Known Space stories.

6 comments
Kevin Maroney
1. womzilla
Sapience isn't necessary for their function, even if they are intelligence-gathering--my camera can do face recognition, so it's "sentient," but it's not sapient in any meaningful way. That doesn't mean they aren't sapient, only that there's no reason to presume they are.

It's possible that the sunflowers are self-seeding, even across interstellar distances, and that they are autonomous. There are other interstellar self-seeding plants in Known Space (the stage trees, from "A Relic of Empire") that are probably artifacts of an ancient technology, and by Occam's Parsimony are thus probably Tnuctipin-created. Of course, they could also have been brought to the Ringworld from a hostworld either by someone who didn't understand them, or by someone who did and wanted to fowl part of the world.

If the sunflowers are programmed to attack any nearby flying objects, they can serve as floating interdiction fields, fowling enemy territories. If the Tnuctipin have the ability to override them, their usefulness expands greatly.
Wesley Parish
2. Aladdin_Sane
My head is spinning considering the details of plant neurons. Animal neurons use fatty tissue - myelin - for insulation (neurons live in a ionic bath of potassium and sodium, so need insulation to operate.). So how would the plant neurons operate?

And the processing power of animal neurons in in the synapse. I am trying rather hard to figure out the plant neuron's equivalent to the synapse, but am having no luck. Perhaps it's an adopted/adapted viral invader?

Otherwise we're looking at a water-powered processor that would use incredible amounts of water and nutrients just to get started in the mornings. And nowhere in Ringworld do we find that amount of water or nutrients anywhere near the Slaver sunflowers.
Doug McElwain
3. dmac44
Per The Ringworld Engineers the back of sunflower bloosoms are "stringy, laced with some vegetable analogue to muscle fibers." These "muscles" are used by the plants to focus their blossom. I assumed a similar vegetable analogue to nerve cells. After all, the Tnuctipin made these from who knows what alien biochemistries.
Wesley Parish
4. Aladdin_Sane
I've just dug up The Ringworld Engineers and skimmed the section. Sunflowers are apparently compatible with the general hominin biochemistry, since the king giant and his band of grass giants are planning on eating the dead and dying sunflowers.

I suppose that the appropriate vegetable muscle "source" is the venus flytrap, since that isn't just an additive growth process - it changes from open to closed and vice versa; and that is probably a "source" of plant neurons, since they react to the presence of insects.

But it still is a leap of several magnitudes from the simple reaction process of the venus flytrap to the proposed simple neuronal setup. I have no problem with the idea of a plant forming a sort-of optical network, since at least one part of the system is already in existence - the chlorophyll in the leaves and in many plants, throughout the upper plant. It should not be too difficult to adapt a viral invader to provide a light cell as a symbiote ... the generation of the fibre cable and the linking would be a major biochemical project.

I'm afraid, with a major part of my (informal) education being in neuroscience, I'll always find plenty of stuff to nit-pick on anything to do with the neurosciences ... :)
a1ay
5. a1ay
There are other interstellar self-seeding plants in Known Space (the stage trees, from "A Relic of Empire") that are probably artifacts of an ancient technology, and by Occam's Parsimony are thus probably Tnuctipin-created.

They are: in "World of Ptavvs", a Slaver character remembers his family having a stage tree plantation, and harvesting the trunks for use as rocket boosters. They weren't created to be self-seeding, but evolved that way later.
a1ay
6. Nessus
I would say another possible source is Concordance Citizens (Pierson's Puppeteers, to you humans), planting them there for some nefarious end much as they wrought the plague which destroyed the superconductors on the Ringworld. Although cowardly, a more insane Citizen such as a scout might briefly work himself up into a manic enough state to manage such a thing.

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