Abstract: The method of making expanded and fiberized tobacco stem and stalk materials having increased filling capacity and suitable for use as filler in smoking articles comprising conditioning said stem material by adjusting the moisture content to a level of at least about 10% to about 50% by weight while maintained at a temperature of about 115.degree. to 170.degree. C. and a pressure of about 10 to 100 psig for a period of from about 0.1 to 5 minutes and mechanically fiberizing the thus treated stem material while it is under a pressure of about 10 to 100 psig between fiberizing surfaces maintained from about 0.05 to 0.3 inch apart. The invention also includes smoking articles made from such expanded stem material having increased filling capacity and lowered "tar" and nicotine.