Concept

Mirror ambiguity — where it appears

A spiral pattern and its reflection have identical counts, pairs and step lengths, so no count can say which way a stem winds. It is why a reversal is recognised by comparing a divergence with its own control rather than by measuring the wrecked stem alone.

Named by 2 essays across one field — each of them below, with the objects they name alongside it.

Two numbers out of the points

A seed head's divergence angle can be recovered from its spiral counts only to within an interval, because a range of angles gives the same counts. On a stem the counts come with lengths attached, two measurements pin two unknowns, and the lattice comes back to the last digit it was built with.

cylinder · cylinder recovery

The shallower front turns over

If reversing a stem means rearranging its whole front, then a stem with a shallow front should reverse more often. Measured across three rungs and four hundred and seventy-three cuts: 6.8 per cent at a front of three, 4.7 at five, and none at all at eight — where the nearest approach is two tenths of a degree away and stays there.

cylinder · coarse rung

Named alongside it

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

Divergence angle Rise Ablation Claim testing Cylinder Fibonacci Handedness Honest limits Identifiability Inverse problem Lattice Measurement

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