Fig. 6.

Higher-number branching, whorls. Again starting from tip growth, shorter pattern wavelength breaks symmetry into higher-number branching events, of three (A) to six (B) structures. The six lobes in B are not the steady-state chemical pattern for the initial hemisphere, but have been stabilized by surface growth. Such simultaneous whorl-forming events are common in plant development, such as flowers and conifer cotyledon formation (C, Larix leptoeuropaea, from Harrison and von Aderkas, 2004). Very high-number whorls, such as in Acetabularia (up to 35 structures), can form simultaneously, but may require prior formation of an annular pattern (Harrison et al., 1981, 1988; Harrison, 1992).