Multicellular

Two questions will occupy us in this column, both of which concern the relationship between the whole and its parts. Let's start with Nir's philosophical questioning: in the animal world (fish, reptiles, mammals and birds) we know that all the organs of the body serve the brain, without a brain the rest of the body has no right to exist. But what happens in the plant world? On which part of the tree can it be said that all the other parts serve it?