Indeed, by far most christmas trees are grown like any other cut-flower. During their growth they are pruned, fertilized and treated to slow their growth to get the 'perfect' christmas tree. If you see such a field you will also notice how absolutely boring perfection is!! The remainder (over here at least) are sold by the owners of natural reserves: a cheap way to get rid of as many of them as possible! The money they make is used to chop down more to keep the heather fields open which would overgrow and change to wood otherwise.
(here an impression at some randomly chosen grower:
http://brinkman-nordmann.nl/fl... )
Those painted Cactus and even worse Echeveria are sold over here too. The latter are painted with glow-in-the-night paints... so do NOT look at this site if you have a weak constitution...:
http://www.greencre8.nl/assort... and yes, there exist people who love this...
Ruud