14. This class comprises all the cone-bearing trees, the annual rings of which are very distinct, and the pores filled with resin or turpentine. It includes some of the most durable and useful kinds of wood.

The pines (Pinus) and firs (Abies) were formerly included in the same genus, but modern botanists keep them separate. The leaves of the pine are needle-shaped and always green; they grow in groups of two, three, four, and five, surrounded by a membraneous sheath at their base, whereas those of the fir rise singly from around the stem similar to the teeth of a comb. The fir-tree is also distinguished from the pine by its growing in a more pyramidal form, and by the character of its fruit.