Mature Heliantus annuus capitulum showing Lucas (76,47) phyllotaxis (mature seed packing).

From: Ryan G. W., Rouse J.L. and Bursill L.A. : Quantitative Analysis of Sunflower Seed Packing.
J. theor. Biol., 147 (1991) 303-328,
(with the kind permission of authors)