1. Start with a seed
The axiom is like the first cell of a plant. It may be only one symbol, such as F, but it contains the starting instruction for the whole shape.
L-System Nature Lab
Grow procedural trees, ferns, algae, vines, and branching plant structures.
How L-systems recreate nature
2. Rewrite the instructions
In the simple preset, F becomes F[+F]F[-F]F. Read it as: grow forward, branch right, grow forward, branch left, grow forward.
3. Draw with a turtle
Imagine a tiny robot with a pen. F tells it to walk forward, + and - turn it, and brackets let it jump back to an earlier branch point.
Explanation
Why tiny rules make huge plants
L-systems are powerful because the same rule is reused again and again. That is similar to nature: a tree does not need a blueprint for every twig. It follows repeated growth habits, and complexity appears over time.
What iterations mean
An iteration is one growth generation. At iteration 0, you only have the axiom. At iteration 1, the first replacements happen. By iteration 5 or 6, the instruction string can become thousands of symbols long.
Why brackets create branches
The bracket symbols work like save points in a game. When the turtle sees [, it remembers where it is. After drawing a side branch, ] sends it back so another branch can grow from the same stem.
Try these experiments
- Raise Iterations one step at a time and watch complexity explode.
- Change Angle to see branches spread wider or grow taller.
- Start with Simple Branching Example first. It has no jitter, so the same grammar always draws the same plant.
- Then turn Jitter up after you understand the pattern. Jitter makes it look more natural, but less predictable.
- Increase Leaf Density to make tips look alive.