The Hierarchical Control of Phyllotaxis

Bolle's phyllotactic theory is enhanced here in the light of recent works which underline the importance of vascular organization in the determination of phyllotactic patterns. It is emphasized that non-vascular plants, such as Fucus spiralis, can reveal how normal phyllotaxis originated. These two approaches to phyllotaxis, with others put forward here, present the problem of phyllotaxis as a matter of hierarchical control, which produces the integrated and simple behaviour of the primordia of growing plants.