Pine - Heartwood/Sapwood?

[Sgian Dubh]

Richard, I will have a proper look tonight (bedside reading) and then stand corrected

In reality, Droogs, I was primarily trying to gently point you to a subtle clarification in your definition of the heartwood being 'dead'. It is dead in the sense that it's no longer growing tissue, and it's role as xylem has changed from it being sapwood transporting water, minerals, etc to the tree's 'engine', i.e., the leaves and has become the tree's supporting structure (heartwood). On the other hand, heartwood needs nourishment to maintain its viability as the tree's structural support, so it is nourished by foodstuffs transported to it by the medulla. Without nourishment heartwood can decay and therefore fail in its role.

I guess an imperfect analogy is to compare a tree's heartwood to the bones in a mammal. Bones support all the loose bits of flesh and gore of the creature towards both the interior and the exterior of the structure they form, and to do this bones need to be nourished by foodstuffs of some sort or another to remain healthy. I assume anyone with medical or veterinary knowledge, biologist, etc would be able to describe in detail how poor my comparison is ... but I hope I can get away with it on this occasion, ha, ha. Slainte.