Plant collecting (growing plants in a greenhouse) doesn't do nature any good,
at least not directly. The grower purchases peat moss which was probably
mined in Canada at the cost the destruction of many cp. The grower uses pots
and heating/cooling. All of this taxes the environment to varying degrees.
However, if a person is caught by the allure of cp or bird collecting, or
herp collecting, or aquariums, this may very well lead to a greater
appreciation for these organisms. Collecting may start as a kind of
proprietary urge toward a big personal collection. But I think that
continued exposure to the hobby will enlighten most hobbyists to the real
plight of plants and their habitats. These collectors may grow to become
real environmentalists! There is less likelyhood they'd be environmentally
concious if they'd been immersed in collecting stamps or classic cars.
Interesting plants such as the Cactaceae, Droseraceae, Nepenthaceae,
Sarraceniaceae, may have been overcollected in the past (and may still be)
But hobbyists now support their preservation and give them some "voice",
even if that voice is ultimately drowned out by the bulldozers. Rare
species in the Cyperaceae, Plantaginaceae, Phytolaccaceae, etc... may go
extinct with few people noticing, and without representitives in
cultivation.
Michael