Phyllotaxis
the spirals are counted, not admired
Concept

Explanation — where it appears

2 essays name this object, across 2 fields. What follows is each of them, and the objects they name alongside it.
120° — a third of a turn3 and 6 — whorled137.51°2 and 3 — Fibonaccirise 0.055 in both panelsthe counts decide, not the eye

What a mechanism would have to show

This site says of every model it draws that reproducing a pattern is not explaining it. That is easy to repeat and hard to make precise. Here it is made precise — a list of what an account of phyllotaxis would have to establish, with each item marked according to whether the models on this site establish it.

mechanism · mechanism claims -2-1.50-1-0.500100120140160180divergence angle (°)log₁₀ of the rise between nodes1,2,32,3,522 × 150 lattices, each solved196 runs drawn

The angle is not the object

Every popular account of phyllotaxis is organised around a number. After a phase spent on stems, forks and frequencies, the number looks like the wrong thing to organise an account around — it is the limit of one path through a branching structure, it is at no fork, and a plant that has it got there by not jumping.

wrong · the tree not the angle

Named alongside it

The objects these essays reach for when they reach for this one.

RiseAttractorAuxinBranchBranch structureCylinderDivergence angleEvidenceFalsifiabilityFibonacciHistory dependenceLadder

All concepts