The ingredient list for bending is
Most people swear by white oak and hackberry as great bending woods. Fir and maple are counted as among the worst. Green wood is best, because it already has moisture in the wood. Kiln dried wood is considered worst because "the wood is permanently set", though others find it bendable if they soak it in water.
Heat is generally applied with steam (in a steam box) or with a heat gun. There are those in the know who say that only hardwoods can be bent. Others (Morris) clearly have experience with soft woods as well. It has been my experience (RAA) that both can be bent, but that while hardwoods need to be exposed to steam for an hour per inch of thickness, that softwoods like pine or cedar only require 2 minutes for a 1/4 inch thickness. Giving 1/4 inch pine 15 minutes will cause compression fractures on the inside of the radius of bend almost every time.
Some links about bending wood are below:
Good general FAQ on steam bending
Link to a homebuilt steamer
The "wood doctor's" sum total of knowledge (actually an excerpt)
Some thoughts on taking wood from the woods LOL and making it straight
Another link about bending
I wish I had a link on bending wood with a heat gun from Rob Macks, the apsotle of the heat gun, but he has not yet put such an essay on his Laughing Loon Shop Tips page. Suffice it to say that some of the advantages of bending with a heat gun include
For an example of the advantages of bending in place with a heat gun, see the page below, where Rick Allnutt needed to reshape all the ribs on an SOF canoe. They had been bent with steam, but were rebent into a different shape with a heat gun while they remained on the gunwales.