Cell area — where it appears
Named by 2 essays across one field — each of them below, with the objects they name alongside it.
Also named here as packing, rim effect — the same set of essays touches all of them, so they are one junction rather than several.
The second moment is the measurement
The mean number of sides in a cellular tissue is six, and Euler's formula leaves it no choice — so it takes the same value on a golden-angle head, a whorled head and a set of random points. The mean squared departure from six varies by a factor of eighty across the same three, and almost nobody reports it.
The six are the spirals
Label every contact between two cells in a seed head with the difference between the two nodes' placement indices. The labels are the parastichy numbers — 34, 55, 21, 89 — and the six sides Euler forces turn out to be about two from one family, one and a half from the next, and one each from two more.
Named alongside it
The objects these essays reach for when they reach for this one.
DisorderEuler's formulaGolden angleLatticeMeasurementPackingRational angleRim effectVoronoi cellsWhorledAboav–WeaireDelaunay