Functions of any living organism are determined by its anatomy. And I am interested how wood anatomy underpins tree functions. My 2015 PLoS ONE paper described wood anatomical variation largely independent of wood density. Here is a figure, which I think nicely illustrates the nature of this variation. And below are examples of real wood cross-sections. Basically, this variation is stretched on the fibre-parenchyma trade-off. On one end of spectrum, wood have loads parenchyma and scarce fibres and on the other end, wood have load of fibres and scarce parenchyma. In general, fibres play mechanical role and parenchyma stores food. Could it be mechanical-food storage trade-off then? It is actually more complicated and possibly, fibre and parenchyma may play multiple roles. Despite my efforts described in this paper, we still don’t understand the functional meaning of this spectrum of variation. Exploring these questions in the future will be very exciting.