In the never ending quest to get elves to live in trees, I am taking things one step further and attempting to get the entire city in a tree. Magic is not in the equation. The tree would start out looking like this from above:

enter image description here

As time goes on, the tree would expand outwards, with the dual trunk marked 'roots' remaining in place while the circle grows. The city is within the circle, as shown.

You can think of it as people living in a hallowed out tree trunk, with one very large exception: the 'trunk' is only located in the area marked 'roots.' The circle part is basically one gigantic root, about as thick as a two story house. It would like this, from the side:

enter image description here

Is this design possible? Is there any reason trees like this would ever exist? This is for a fantasy novel, so you can make a few things up like creatures if necessary. My idea is that the tree creates a safe haven for animals (and people) within the circle, and then gets a lot of nutrients from them.

Details (as requested by Lord Dust)

  • While tree shaping is not entirely out of the equation, I would prefer not to use it, as it takes a long time and is therefore impracticable for immediate housing purposes.
  • The elves are human-sized, maybe six inches higher.
  • The city needs to be able to accommodate around 5000 people. I've never really thought about it, so that estimate is flexible. It is a capitol though. (Think really big community instead of city).
  • The tree does not need to be of any particular type.
  • The city is located on the edge of a forest, at the foot of a mountain (about 3000 meters high, little to no snow). The entire area would be at about 50˚ North. It is sitting on mostly plains-type ground, used to fog from a nearby forest river. Probably generally moist ground, though it dries out in the summer, reaching temperatures of around 80-90˚F.
  • The tree should be one of many. This is not mandatory, but would be quite useful.
  • As for modifications, certainly it can be modified. The main thing is that it has to be found more or less habitable (meaning the circle is in place). - Certainly tree growing can occur later, just not to start.
  • It doesn't have to be a tree, but it does have to be as tall as one, as I am envisaging it overshading at least part of the city.
  • The tree was found at its current size. It is however alive and growing, though likely very slowly. (Speed is flexible.)
  • $\begingroup$ All right, so no shaping, fantastic or otherwise. How big are our elves? How big is this city? Need our tree be of any particular sort (esp. coniferous or deciduous)? What sort of terrain is this? Is it even in a forest? Must this tree be unique, or must it be one of many? Can, or must, the tree be modified in ANY way? Must it even be a tree, or just something that resembles one? Does the tree start out village sized, and grow, or was it found like this? If it grows, will it do so at a perceptible rate? $\endgroup$
    – Lord Dust
    Commented Sep 1, 2016 at 23:41
  • $\begingroup$ @LordDust I've edited in some details. Let me know if you need more information. $\endgroup$ Commented Sep 2, 2016 at 2:33
  • $\begingroup$ Related post. It isn't exactly the same, but could give you some inspiration. $\endgroup$
    – Rick M.
    Commented Apr 23, 2018 at 19:48
  • $\begingroup$ sounds like a rare form tree cancer $\endgroup$
    – Till
    Commented Jun 5, 2018 at 13:17

3 Answers 3


It seems natural that elf trees grow out of elf circles (more commonly called fairy rings). These rings are formed by mycelia, or mushrooms. The mycelia alter the soil composition around it, causing the grass and other plants in the area to be affecting, causing the visual effect of the circle on the surface event when the mushrooms are not sprouted. Sometimes the mycelia depletes the soil nutrients, causing a circle of dead grass. Other times it produces chemicals beneficial to the plants, causing them to grow more lusciously than their neighbors. Our elf tree enjoys a symbiotic relationship with a type of mycelium. So much so, that the trees have adapted to grow their roots in the circle in order to maximize the amount of nutrients provided by their partner mycelia. The additional nutrients also cause the trees to grow spectacularly compared to their neighbors, large enough to protect a village of elves.

  • $\begingroup$ Could a tree grow so spectacularly as to grow significantly faster than other trees? 2+ meters a year? I heard that the fastest is 1 meter a year, hence the figure. $\endgroup$ Commented Aug 31, 2016 at 20:52
  • $\begingroup$ Is that rate of growth a requirement? $\endgroup$
    – Lord Dust
    Commented Sep 2, 2016 at 0:25
  • $\begingroup$ No, I'm just curious. $\endgroup$ Commented Sep 2, 2016 at 2:33
  • $\begingroup$ With a pretty border of mushrooms outside the walls. $\endgroup$
    – Spencer
    Commented Nov 23, 2017 at 11:32

Imagine an area much like the eastern face of Canada's Rocky Mountains, but earlier in prehistory, when the central plains were, in fact, an inland sea. Giant prototrees inhabited the shallows of this sea, and root formations where the rooted tree did not begin by growing vertically were not unusual. Very wide roots systems and bases in the sedimentary swamps, on the order of hundreds of meters wide, were not uncommon, supporting trees up to 1000m in height.

Later on, the seas retreated, and erosion of the sedimentary sea bed began. Wide swaths of the giant forests died out, and were replaced by smaller trees more adapted to the drier environment, as in our world. However, in one region, this didn't happen.

Here, volcanic intrusions from beneath the seafloor (such as our own Devil's Tower were relatively commonplace. Over an area of roughly 200 km², these intrusions were revealed to various altitudes by erosion of the surrounding sediment. By chance, the formation of these extrusions included substantial amounts of minerals such as selenium that were very favourable to the growth of these prototrees. The root systems and broad bases of these trees would often grow to encompass these round intrusions, developing a trunk above a certain height on the "southern" (ie. dominant sunlight) side of the rock. Although single trunks are most common, double or multiple trunks are not unusual. Since these "trees" are not really trees in the modern biological sense, the method of growth and renewal is based on cannibalistic tendencies of the plant. Rather than a single specimen growing to an enormous age, young individuals attack the older main body constantly with a rapid growth, increasing the girth and height of the plant in successive layers. Thus, these "trees" are actually quite young, and largely unscarred.

The largest of these igneous intrusions was about 3km in diameter. This rock formation was eventually completely encircled by prototree growth. A number of smaller secondary trunks grow from this ring, but the primary trunk is a double trunk system facing just west of south. This particular rock formation, like many others, protruded quite far above the forest floor. At some relatively recent time (geologically speaking), the rock formation, intruded by root systems below the surface, broke off and collapsed off to one side. Fortunately, the trunks were not taken down at this time. Unfortunately, the spectacular size of the primary trunk means that without the protection and occasional support of the central rock, it will soon (relatively) collapse.

Our elves will have had to carve a gate through the encircling tree below the main trunk system, and will have to have found some way to arrest interior growth of the tree into the ring. Not only is it fortunate for them that the largest igneous intrusion developed in this unique way, but it is also serendipitous that they were there and required a home after the rock broke off, but before the central ring grew over.

It's all pseudoscience, or at the least highly speculative, but it seems plausible to me. The conditions for this seem highly unlikely; then again, stranger things have happened, generally in Australia.

  • $\begingroup$ The 3km diameter was chosen by doing a quick Wikipedia survey of the land area of town of about 5k population. It seems overly big, both for the rock formation and the "tree". I'd have to recommend that our elves not be claustrophobic, and be willing to live in a vertical arrangement on the "wall" in a smaller diameter formation. $\endgroup$
    – Lord Dust
    Commented Sep 2, 2016 at 17:01

Something similar to a Strangler fig, though rather than a single plant it might be many would work. Rather than a single large tree, it would be a fast growing population of trees, possibly aminable to coppicing, possibly this could be a combination of a primary 'structural' plant, with a vine like plant that grows fast and thickens to a woody, strong structure.

While nothing like this exists in nature, over time you have a central tree that dies and spreads, and strangler vines acting much like a natural lumberjack, and then dying as nutrients run out near the centre.

Due to this you wouldn't have a nice round circular trunk, but rather a interconnected series of naturally tangled living and dead wood.


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