RHIZOTRON

Tropism 01 · toward moisture

It grows toward water it cannot see.

A root tip does not plan a route. It reads a gradient — a faint chemical rumour of moisture in the grains around it — and leans a few degrees that way each time it extends. Repeat that ten thousand times and a blind tip walks a clean line to a pocket buried forty centimetres off to one side.

Every pocket you bury rewrites the map. Drop one near the surface and laterals fan up to meet it; drop one deep and the taproot leans and commits. Nothing is scripted — the tips are only ever solving for the next eight millimetres.

The method · space colonisation

Ten thousand small, greedy decisions.

The soil is seeded with invisible attractors — the moisture the root is chasing. Each step, every tip looks only at the attractors within its reach, averages the direction to them, adds a downward pull for gravity, and extends eight millimetres. Attractors it consumes disappear; new tips branch where several pull at once.

There is no global plan and no undo. The elegant taproot, the reaching laterals, the swerve around the stone — all of it is emergent, the residue of a tip that could only ever see the grain in front of it. This is the Runions space-colonisation model, drawn live in SVG.

A root spends carbon where it earns carbon.

Secondary thickening · load follows flow

Tropism 02 · around the obstacle

The stone, and the routes that pay.

Meet the buried stone and the tip does not stop — it slides along the face and rejoins its descent, the way a real root reads pressure through its cap. Dry dead-ends stay hair-thin.

Every route that reaches water thickens. As tips draw moisture, the path back to the crown carries more flow, and the observatory paints that flow as width — so the map of what worked is written straight into the plant.