lemonnice-burying the placenta under an apple tree means you get lovely apples the next year.
For us it was a part of ds's naming ceremony, transition to independent life etc etc. It looked after him (with help from me) for 9 months, so wanted to give it a decent send off! Each to their own.
I will say that I have NEVER hugged a tree though.
I too would not plan for ds to be there. I don't think that would be fair on him, he would need to have the option of leaving if it got too much.
I do think if there is any chance of a child being present, they need someone specifically to look after them, and that person needs to be confident and not about to go into a flap during the labour. In our case this means dp will probably look after ds. If the labour is long enough for my mum to get there, she will take over at some point. The important thing for me is that both carers are comfortable and confident about my birth choices, and so should be able to communitcate to ds that everything is fine, normal, etc. I just don't know anyone else who has a really down-to-earth, get-on-with-it attitude to birth apart from these two .