Cork is not a plantation wood exactly (although there are a few new plantations popping up in Asia), but it is often lumped in with them. It is most definitely one of those constantly referenced green products and for once, I really can find very little gray about it… it's a great product.
As everyone knows, cork is actually the bark of certain oaks-you can peel it off and it grows right back, with a harvest from a mature tree coming every eight to 15 years. That's pretty impressively renewable. And of course as a result, it qualifies as a "rapidly renewable" product for LEED and other green building programs.
Cork has a couple of extra green features-flooring is usually made with the leftover cork fiber that develops in processing the bark for other uses, particularly wine corks. That means recovery of the original material is maximized. It is also very recyclable as a product-some cork floor is made not from the industrial waste, but from post-consumer waste-the recovery of used wine corks and other products.
Cork flooring is produced by taking all those tiny little pieces, mixing them with glue and baking up sheets. Like bamboo, cork can require a bit of extra processing energy and glue when compared to many other flooring forms. However, as with bamboo, most all companies use low-VOC glues. The extra processing required is one of the few "gray" areas in the greenness of this product. (Another gray aspect is that it also can have a shorter lifetime of use than some other products, being difficult to sand or refinish.)
On the plus side, cork has some natural resistance to mold, bacteria and insects. This resistance is from the material "suberin" present in the bark. "Suberin" is named after the species of oak that provides us with cork, Quercus suber. Suberin also makes cork slightly water resistant. (But not waterproof, so treat it is as you would wood, with proper sealing and with moisture barriers as appropriate!)
Cork has great insulating properties-it is often used as a sound barrier or to control heat flow. Underlayment is a common usage for cork, both as a sound barrier and to give the floor that little extra spring. All in all, it's a multifunctional and overall, very green product.
(Pictured is a cork floor by Kentwood.)