When is a tree not a tree?

When is a tree not a tree?

Answer - when it's a sapling.

But what, one of us asked the other day, is a sapling? When does it stop being a seedling and when does it become a tree?

The answer proved somewhat elusive. We finally concluded that it was a pretty loose term for a young tree. But, on route to this conclusion, we came across a number of definitions which conflicted. More than one site seemed to have directly translated 2-4 cm into 2-4 inches (or vice versa!!)! What was particularly amusing was the idea that the following would have fitted into one or other definition - a forty year old Oak tree, a fully grown Apple tree, and a twenty five foot high Birch...

Among the definitions were the following:-
A young tree, but bigger then a seedling.
A small tree, usually between 2 and 4 inches diameter at breast height.
A young tree normally more than 4 1/2 feet (1.5 meters) high and less than 4 inches ( 10 centimeters) in diameter
A loose term for a young tree no longer a seedling but not yet a pole, about 1 - 2 m high and 2 - 4 cm DBH (diameter at breast height), typically growing vigorously.
A tree more than 0.9 in (3 ft) in height and less than 10.2 cm (4 in) in dbh.
A loose term for a young tree more than a few feet tall and an inch or so in diameter.
A young tree, shorter than an adult and not yet producing seeds.