One year, grown once and replayable. Nothing decides the shape: each branch reads only what is directly over it, how far out it has got, and how far the water must travel — and that settles whether it bears leaves, drops a prop root, keeps reaching, or is let go. Thickness is derived rather than drawn, from the leaf area each branch feeds. The panel on the right is the plant; the drawing is only a picture of it. Move a knob and the tree does not start over — what it has already grown is fixed, and the new instructions reach forward from wherever it has got to. Scrubbing back to look never changes anything; the marks under the timeline show where each change of plan took hold. See a single frond unfurl →