Tree ideas for Terasology. For forum discussion. As input of ideas. For people who are reading the list and talking about Terasology. From woodspeople, aka Cynthia Kurtz and her son. Who are thinking about this.
First: problems with L-systems
Why do I (the mom half of woodspeople) not like L-systems for growing trees and plants? Why do I not like them now and why did I not like them then? Back then, I was writing a garden simulator for regular people to use to learn more about how plants grow and how soil works. I wanted people to learn about botany and photosynethesis and light and shade and water and nutrients and all that. The problem with L-systems then was that there was no meaning in it. Yes, you could produce things that looked an awful lot like plants. And you could even produce things that looked like healthy plants and sick plants and shaded plants and plants growing on nutrient-poor soils. But you couldn't say those things and get those plants. You had to translate everything into a series of logical transformation rules that make no sense to 99% of regular people trying to learn about plants. That's why I didn't use L-systems before. I wanted people to be able to get into the simulation and really play with it.
Why do I not like L-systems for plant and tree growth in a fun imaginative game now? For the same reason. People want to get into the simulation and really play with it. They want to play with funner things than just an array of slightly different boring tree shapes. One of the things people liked about our old plant drawing system was that you could produce truly one-of-a-kind plants, strange unearthly things, by futzing around with the parameters, by thinking about the parameters (like “what would happen if there was no apical meristem but there were loads and loads of axillary meristems?), and by breeding random things. This is harder to do with L-systems, unless you are a L-systems genius. Most people just can't think in those abstract terms without some help.
Second: amazing trees
We (“we” is my son and I) started looking through tree field guides to think about tree types and shapes and so on. We moved from that to looking at the “edible plants” book. What we realized was missing from our exploration was not the shapes of the trees but the cool things you can do with them. People who really study trees don't get excited about shape, they get excited about the features of trees: how they grow, where they grow, when they grow, what you can do with what they grow, and what that all means.
So then we started looking up pictures of "amazing trees" on the internet. We quickly found several "top ten" lists of trees that show exactly why trees in a game like TS just beg to be more amazing than amazing. Here are some links to such lists:
http://www.neatorama.com/2007/03/21/10-most-magnificent-trees-in-the-world/
http://www.mnn.com/earth-matters/wilderness-resources/photos/worlds-7-most-amazing-trees/the-tree-of-t%C3%A9n%C3%A9r%C3%A9
http://webecoist.momtastic.com/2008/12/10/bizarre-exotic-amazing-trees/
Now I started to get an idea. One of the more boring aspects of MC is that the trees all look pretty much the same, but more importantly they all do the same thing (for the most part). They have slightly different growth patterns, slightly different bark patterns, slightly different leaves, and slightly different uses. But real trees are amazingly diverse and diversely useful. 
Third: real, better, useful
We started to look at all the trees in our field guides and on the "top ten amazing trees" lists. We start to think: what if all the trees in TS had these qualities:
1.	they were sort of like a real tree, one considered amazing in reality (by somebody)
2.	they were even more amazing than the amazing trees, exaggerated versions of them, fantastic versions
3.	players could do something as a result of each amazing quality of these trees
Fourth: lots of crazy tree ideas
To explore this, we started building a sort of library of amazing trees TS could have, based on real trees we knew or knew about. Here is what we came up with so far.
Name, real example	Exaggeration	Uses	Things you could do to/with them	Frequency, Growth pattern	Dangers	
Lift tree, like sequoia	Not only is it super tall, but sometimes there is a ladder inside you can climb up. Also, real sequoias have whole ecologies growing in their branches. This could happen in the lift tree. Special animals, special foods ... There might even be pre-built houses in them, high up.	Quick safety when traveling. Instant houses. Just really interesting places to discover.	Could burrow through (to some extent) without killing it. (Like sequoias with car tunnels in them.) Could live in them.	Rare, slow	Could fall from high up.	
Spiral tree, like various trees that grow in spiral patterns	You can walk up the staircase.	Quick look around	Maybe you could encourage them to grow in particular directions, then graft different spiral trees together to create an above-ground transportation network, on which rail cars could move.	Common, fast	Could fall but not likely; leaves would protect you	
Tent tree, like spruce or fir	Like a giant tent underneath, with central trunk but leaves all around reaching down to the ground.	Have to dig under or break some leaves to get in, but once inside monsters can't get at you. Quick refuge in trouble.	Could encourage to grow more widely? Could dig down under main trunk to create larger cavity inside.	Medium frequency, medium growth	Could collapse? Some monsters could break leaves? 	
Bulb tree, like baobab	Has spherical bulb in center, but it's really really big. 	Can be a house (or prison). Sometimes contains water (useful in desert).	If you hollow out the center carefully, it will grow larger. 	Rare and only found in deserts; very slow growth.	Could get trapped inside somehow, could drown inside	
Hobble tree, like Pirangi cashew tree, hobblebush	Tree branches come back down to the ground and re-root, making a sort of “basket” shape surrounding an area	Can be a frame for a house. Can trap monsters. 	Could encourage them to grow in a regular pattern to make a better trap?	Found near streams; fast growth.	Could get stuck inside? When running fast could get lost in maze of branches touching ground.	
Many tree, like clonal trees like “Pando”	Many trees in one area are connected by vast underground root system.	Once you tap into the root system you can use it to travel long distances underground in safety.	Could encourage roots to graft together to create more connections in underground system.	Forests, very rare.	Could get lost in root system, water could come down int o it when it rains and drown you. Could be worms down there that eat people.	
Tap tree, like desert trees with very long tap roots	Tree has huge root that goes down far into the earth.	Could burrow down in tree to mine. Wood is easier to break/cut than stone, hence mining is easier. Also a safe base away from monsters.	Can hollow out base if you are careful. Can get water there also. Can encourage tree to grow tap root deeper by reducing nearby water supplies or manipulatig underground water supplies.	Deserts, rare.	Could drown; could fall down into bottom of root. Rarely one of them will grow right out the bottom of the world. Could die if too much water is removed nearby.	
Scupltable tree, like trees used for horticultural shaping	These trees can be shaped into many shapes and not die. 	Can build trees into shapes for many purposes: decoration, defense (a tree fence), habitation, trapping.	There is much to know/learn about how to sculpt trees properly.	Forests, plentiful (but hard to control).	Could get trapped inside; tree could fail to grow as expected.	
Fire trees, like pioneer species	These trees only grow after a forest fire.	They might have something special you need, like I don't know, fire berry or something.	Controlled burnings would encourage fire trees to grow.	Burned land, common.	Danger of fire.	
Enlightenment tree, like bodhi tree	If you sit under it you will find out things you wouldn't know otherwise.	Finding out things, like where ores can be found.	Find these trees, map them, go to them regularly.	Anywhere, but very rare.	Danger of becoming too wrapped up in trance listening, unable to get away.	
Extreme seasonal trees, like trees that shed their leaves	Not only lose their leaves in the  winter, but disappear entirely. Or change to some other shape.	Temporary growing, covenient disappearance at times.	Can “trick” trees into thinking it is winter or summer using steam heat or refrigeration. Sort of like programmable trees.	Forests, medium.	Danger of them disappearing at the wrong time (when you are on them) or appearing at the wrong time (when you are where they should be).	
Sharp needle trees, like acacias	Needles, but REALLY SHARP ones	Great weapons if you can get hold of them safely. 	Harvest them, farm them, plant them as defense hedges.	Dry areas, common.	Getting poked to death.	
Changing bark trees; on lots of trees, bark changes with age from smooth to rough	Start out looking one way, then as they grow change to look completely different.	There is something useful about both the young form and the older form.	Find out when/where they are growing and harvest them at the right times.	All over, common.	Getting them at the wrong time.	
Poison trees, like allopathic species like walnut	Kill all other trees around them, and maybe other things too.	Plant them as defensive borders. Use them to clear wooded areas. Also their wood makes a useful poison.	Plant, cultivate, learn about.	All over, but rare.	Getting poisoned	
Knee trees, like trees with aerial roots (banyan, strangler fig)	The aerial roots move around and can trap players who are not careful.	Could build traps with them.	Learn about. With much knowledge you might learn to control the movements of the aerial roots.	Swamps, common.	Getting trapped	
Nurse trees (like grey birch)	Grow for only a short time then die, predictably. (Grey birch do this and shelter new seedlings of pine, then die off just when the pines need the light.)	Use for temporary needs? 	Learn about how long they live?	Forests, medium.	Not knowing how long they will live and planning wrong; disappearing under you.	
Garbage trees, like trees that grow best on poor soils	Grow ONLY on ruined spaces.	Use to rehabilitate areas ruined by people doing stupid things. Maybe fix holes, fire damage, griefing, etc.	May be tricky to grow?	Ruined land, medium.	Not growing them right, they don't grow, nothing is fixed.	

Fifth: System that can make this happen

Obviously the thing to do is not to hard-code these tree types in, but to create a system in which creating all these tree types is a matter of specifying a bunch of parameters that make this all happen. That is the part of the thinking I/we have not yet got to. 

We pause now to see if anyone else likes this idea. Otherwise there is no point going further along this path.

Why do we like this idea? A few reasons.
1.	It is imaginative and fun. 
2.	It captures some of what real people do with real trees. Most people throughout history and in non-techologically-overrun areas know trees by what they do and are good for, not what they look like. This is what is fun about trees. Hence it makes sense that fantastic trees should have the same criteria.
3.	A system that was able to produce this list (which is based on looking at some amazing but real trees people have been looking at and using for tens of thousands of years) would also be able to produce other amazing trees that could exist but don't happen to.
4.	Regular people would be able to use such a system to create even more amazing trees without having to understand the difficult logical specification system of L-systems, which is a barrier to many. More people, more ideas, more fun.

Over to you :-)   woodspeople