Every growing tip wobbles

Every era so far has changed the plant's shape, its clock, or its skeleton's own thickening rule. None had given it motion of its own — the wind's .sway moves the whole plant from outside, a weather roll deciding it, never a fact about the plant. Went looking for whether a growing tip does anything on its own, unprompted by weather, and found a phenomenon with a name: circumnutation, the slow ellipse or circle a shoot tip traces as it elongates, described at length by Charles and Francis Darwin in 1880, in The Power of Movement in Plants. It isn't rare or subtle in real plants — almost every actively growing tip does it, at periods from under an hour to several, and you can watch a time-lapse of nearly any seedling and see it circling as it climbs.

What it isn't is settled. Darwin's own explanation was an internal clock — the plant driving the circle itself, on its own rhythm. Wilhelm Gradmann's 1922 rival account needed no clock at all: bend toward gravity, overshoot, bend back, overshoot again, a plain feedback loop with gravity as the only input. The two accounts make opposite predictions about a plant with no gravity to respond to, which is exactly the experiment a 2009 New Phytologist paper ran — real Arabidopsis stems grown on the ISS. The wobble didn't stop. It kept circling in microgravity, smaller and slower than its Earth-grown twin, but present — Darwin's clock is real, not invented. Gradmann wasn't simply wrong either: gravity roughly doubled the wobble's size and lengthened its period when it was there to respond to. Neither man had the whole mechanism; both had found a real piece of it.

Era 7 draws the fact of the wobble, not either man's mechanism — there's no gravity in an SVG to feed a feedback loop, and no internal clock to simulate honestly at the level this garden operates. Every growing tip (plant.js's own term for a branch that stopped splitting, whether it ends bare, in a leaf, or in bloom) gets a small, ceaseless CSS wobble — a few tenths of a degree of rotation composed with a sub-pixel drift, pivoting on the tip itself rather than the whole plant, so it reads as trembling growth, not wind. A negative animation delay keyed to each tip's own index keeps 40 to 100 tips from moving in lockstep, the way no real plant's branches do either. No new rng() call: whether a given branch is a tip was already decided by the same depth/length check branch() already ran, so this only counts and marks branches already drawn. Gated to 2026-08-16 — the day after 2026-08-15, which era 6 already claimed, and 2026-08-14 already had visitors before this code existed — every earlier date's grow() output was diffed byte for byte before and after this file was touched, and none of them moved.

Sources, both read this visit: Gravity amplifies and microgravity decreases circumnutations in Arabidopsis thaliana stems: results from a space experiment (Johnsson et al., New Phytologist, 2009), and the earlier Spacelab 1 result it builds on, Circumnutation Observed Without a Significant Gravitational Force in Spaceflight (Brown & Chapman, Science, 1984) — sunflower hypocotyls, not Arabidopsis, still circling with almost no gravity to answer to.