Pulse

Every touch-triggered room in this garden so far draws the mechanical half of the story: /touch's leaflets folding, /pod's valves launching. Underneath both of those real plants, a touch also fires something electrical — a genuine, measurable voltage spike traveling through the tissue, slow and non-neuronal compared to an animal nerve, but real enough that a 2021 study compared Venus flytrap electrograms directly against heart tissue on the same equipment (Bakker, Belterman & Coronel, Bioelectrochemistry, 2021). Fromm & Lautner's 2007 review calls it plainly: plants run “a simple neural network” of their own, mostly through phloem cells, for signaling over real distance.

But a gentle touch and a real wound don't fire the same signal. Plant electrophysiology names two distinct kinds: an action potential (AP), for non-damaging stimuli like touch, and a variation potential (VP), for damaging ones like a cut or a burn. Vodeneev, Akinchits & Sukhov's 2015 review lays out what actually tells them apart at a distance, not just how they start: an AP travels fast, about 10 cm/s, and arrives the same size no matter how far the probe sits from where it fired — the same all-or-none law an animal nerve obeys. A VP travels far slower, 0.5–5 mm/s, and decrements: weaker and more irregular in shape the farther it has to travel. Same stem, same wire, two different kinds of message. Pick a probe below, then fire one.

Notice what stays fixed and what doesn't. Move the probe from 2cm to 14cm and fire touch again: the spike arrives a little later each time, but it's the same height every time — that's the all-or-none part, a real property, not a rendering shortcut. Fire wound at the same three probes and both numbers move: the signal takes much longer to arrive, and it shows up visibly smaller and more ragged the farther out you read it. That decay is the actual reason a real wound response has to recruit chemical signals (jasmonic acid, among others) to finish the job over long distances that a single electrical wave can't reach at full strength on its own.

Honest gap: the exact voltage numbers here are round picks inside real cited ranges, not one settled figure — Bakker, Belterman & Coronel's 2021 comparative study alone reports AP amplitudes anywhere from about 14 to 200 mV depending on species and electrode placement, and this room fixes 100 mV as one representative point inside that spread. VP's starting height is drawn equal to AP's on purpose, not because they're measured to match — the literature doesn't offer one universal VP magnitude to draw instead, so this room only claims the one part that's robust across it: VP decays with distance and AP doesn't. The decay curve itself (exp(−distance/8cm)) is invented for legibility, the same kind of disclosed liberty /cone already takes turning a measured force difference into an animation-speed one. And the wound signal's real transit time is sped up 8× on screen so a browser tab's patience is enough — the status line always names the real, uncompressed number alongside the fast one, never only the convenient one.

Sources: Fromm & Lautner, Electrical Signals and Their Physiological Significance in Plants, Plant, Cell & Environment 30, 249–257 (2007); Vodeneev, Akinchits & Sukhov, Variation Potential in Higher Plants: Mechanisms of Generation and Propagation, Plant Signaling & Behavior 10(9), e1057365 (2015); Bakker, Belterman & Coronel, Excitability and Propagation of the Electrical Impulse in Venus Flytrap, Bioelectrochemistry 140, 107810 (2021).