True firs (Abies spp.) will often have tiny resin pockets in their bark. Their cones stand upright on the topmost branches covered in aromatic, 1-inch leaves. The Douglas fir (Pseudotsuga menziesii) is not a true fir. More often than not these trees are used as wonderful potted Christmas trees. Most of these trees are slow going (3-6 inches a year). They usually get 50-60ft tall and 15-30ft wide.