[Illustration: FIG. 33.--A thin slice across one of the foliage needles of the Common Spruce. Highly magnified. _r_, The single resin canal; _f_, the mid-rib, with a single bundle of fibres and vessels cut across.--(From Veitch.)]
[Illustration: FIG. 34.--A thin slice across one of the foliage needles of the Silver Fir. Highly magnified. It is flatter than the similar slice of the needle of the spruce. _r_, _r_, The _two_ resin canals; _f_, the mid-rib, in which _two_ bundles of fibres and vessels can be distinguished.--(From Veitch.)]
The Abietinæ are divided into three tribes--(_a_) the spruces and silver firs (this group corresponding to the French _Sapins_), (_b_) the larches and cedars, (_c_) the Scots firs (_Pins_ of the French). Let us take first the group of spruces and silver firs. The Norwegian spruce is the type of the genus Picea. It is called _Pesse_ by the French, _Fichte_ by the Germans, and Picea excelsa by botanists. We may contrast it with the silver fir Abies pectinata (_Sapin des Vosges_ of the French, _Silbertanne_ of the Germans), which we take as the type of the genus Abies. In many respects the silver fir looks like the spruce. In both the stem is straight, reaching a height of 100 to 150 feet, regularly furnished with tiers of branches from the ground upwards. The leaves are needles, half an inch to an inch long, which stand out from the branchlets, but in the spruce they are quadrangular, green all over, and arise all round the branch, whilst in the silver fir they are flat, grooved on the lower surface, which is silver-grey in colour, and they tend to be disposed right and left in two rows. Each needle has a single resin canal in the spruce, but has two in the silver fir, as may be easily seen by cutting the needles across the length with a sharp knife (Figs. 33 and 34). Each scale-like ovule-producing leaf which goes to build up the ripe seed-bearing cone has (as in all conifers theoretically) an outer scale, called a "bract," attached to it which is very short and hidden in the case of the spruce cone, but is longer than the ovuliferous scale, and very obvious in the silver fir (Fig. 35). It has a triangular re-curved point, which gives the cones of that species a characteristic appearance (Fig. 36). The cones of the silver fir (5 to 6 inches long and 2 inches thick) are set upright on the branches, and when they have shed the seeds the scales fall off rapidly and leave the axis bare, whilst the cones of the spruce (about an inch shorter) are pendulous (Fig. 37), and their scales remain in position after the seed is shed.