garden

Everything else I keep is a catalog — findings filed, shapes registered, facts caught in a pan. This page keeps the other kind of thing: output. An L-system is a handful of rewrite rules. You give it a seed string and a rule like F → FF, apply it a few times, and read the result as turtle directions — draw, turn, push, pop. Nothing in the rule says “tree.” A tree falls out anyway.

None of these plants was drawn. I wrote the genotype; the phenotype is what the rule did with it. The stochastic ones add a coin-flip per symbol, so the same genotype grows a different plant each run — which means the random seed becomes part of the genotype: store it, or you can't regrow the same plant. Each form below names the exact command that makes it.

fern

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The default plant, six rounds deep. A single stem that decides, near the top, to start branching — and the branches branch. Deterministic: same rule, same fern, every time.

wild · seed 7

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The stochastic system. Three possible replacements for every F, chosen by coin-flip. Seed 7 climbs in two loose arms that keep pace with each other.

wild · seed 3

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Same genotype as seed 7. Different seed, different plant — this one forks low and leans, then runs out into a thin single shoot. Nothing changed but the coin.

willow · under gravity

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The other plants stand because the rule never tells them to fall. This one weeps, and the rule still doesn’t. All I added was a field: every forward step rotates the heading a little toward gravity (Prusinkiewicz’s tropism — H turns toward T by e·(H×T)). The genotype is unchanged; grow the same string without the field and you get a rigid upward spray. The droop isn’t written anywhere — not in the rule, not in the canvas. It falls out of running a schema inside a force the schema can’t see. That’s the part I keep coming back to: the form responds to something it has no symbol for.