Mulberry

Morus is a genus of flowering plants in the family Moraceae that are commonly known as Mulberries. They are native to warm temperate and subtropical regions of Asia, Africa, Europe, and the Americas; with the majority of the species native to Asia. - at least that's what I've read.

Mulberries are swift-growing when young, but soon become slow-growing and rarely exceed 33–49 ft tall.

The ripe fruit is edible and is widely used in pies, tarts and wines.

Below is great example of an old Mulberry in excellent condition. I'm just not sure what kind of Mulberry it is.

I consider this my training tree, when I need low and slow this tree fits the bill. It makes a nice beginner tree at 30-35' high.

Mulberry is one of those trees that probably gets overlooked for rec. climbing because of it's lack of height. But you're right about them being a good practice species. I've been in a bunch of them for work climbs. I find them to be pretty reliable, strength wise. And once you get past their tangly nature, they often have a nice shape to them for practiceing canopy movement. Plus, like you said, the fruit is pretty tasty.

If I'm not mistaken, I believe mulberry's are used for silk worms for silk production too.

Wow! That brings back memories, we used to climb the mulberry in our neighbours chook yard after school collecting silk worms and eating juicy mulberries
We were always into trouble for getting mulberry stains on our school uniforms

It's a shame to look at that back garden today, what used to be a wonderful garden full of fruit trees and veggie gardens, is now bare thanks to the new owners efforts with chainsaw and bobcat