ORIGINAL: Rodney
I cut most of my wood for the bigger planes from white pine. By going through the 1 X ?? boards at the local lumber yard (you do need a lumber yard that lets you select the boards you want) I find a lot of boards that I can get 6 to 10 foot clear straight close grained material out of. True, more knots than on other types of wood but, by careful selection you can find very useable areas that you can cut stringers and spars from. It is almost as strong as Spruce and works out very well. I use a 10 inch table saw (a 40 year old Sears) that I can cut pieces as small as 1/16 square on up by using a hollow ground blade and a zero clearance insert on the saw.
I agree with the use of a hollow ground or sometimes called planer blade. It will require sharpening and many of us are spoiled by the use of carbide tipped blades but the hollow ground blade does a great job of producing quite smooth cuts and will cut easily if kept sharp. My point in posting the additional comment to Rodney's... is to remember that modern plywoods use glue that is not very friendly to other than carbide blades and will dull a hollow ground blade quickly... so after ripping the spruce... and before using the saw to cut any plywood... return the carbide blade to the saw.
Also, it is better to rip 2-3 inch sheets slightly thicker than wanted with a conventional carbide blade, run them through the planer/surfacer to size the thickness if one is available and then rip them to width using the planer blade. The reason is to avoid cutting thicker materiel with the planer blade as it will have a good bit more cutting drag and thus propensity to heat up.
Used correctly, a planer blade is a wonderful thing... used wrongly it's a pain.