[Illustration: FIG. 95.--WEYMOUTH PINE (_P. strobus_).]
[Illustration: FIG. 96.--SPRUCE FIR (_Abies excelsa_).]
This genus includes all the Spruce Firs, and they are readily distinguished from the pines by their drooping cones (see _a_ in _fig._ 96), the scales of which are not thickened at the tip, but drawn out into a thin brittle membrane; and their leaves, which do not grow erect in sheaths, but in rows standing out from the branches (_b_), and which being the same on both sides, look as if two had grown together to make one. The difference between the Pines and the Firs will be seen clearly by comparing _fig._ 96, which represents a branch of the Spruce Fir, with _fig._ 97, which represents a branch of _Pinus pumilio_, a dwarf variety of the Scotch Pine.
[Illustration: FIG. 97.--_Pinus pumilio._]
[Illustration: FIG. 98.--THE SPRUCE FIR (_Abies excelsa_).]
The common Spruce Fir (_Abies excelsa_) is a tree of stately growth, with an erect pyramidal form, and numerous tiers of drooping branches. It is the loftiest of European trees, having been found in Norway 180 feet high. The crest of the male flower is larger than in the genus Pinus, as shown at (_d_) _fig._ 98, in a magnified side view of one of the cells of a male scale (_a_), from which the pollen has been discharged, the empty case being shown at (_c_). The female scales (_b_) have each a small bract at the back, and two seeds inside, (_e_) the wings of which have each a little cavity at the lower part in which the seed lies, so that it is naked on one side, and clothed by the wing on the other. The Spruce Fir bears cones when the trees are of a very small size; and these cones are very ornamental when young, being of a rich purple, while the male catkins are yellow tinged with red at the base. The sap from the Spruce Fir does not flow freely when the bark is wounded, as it does from the Scotch Pine; but oozes out gradually, and is what is called Burgundy pitch in the shops. Spruce-beer is made from the young shoots of the American Black Spruce. There are many species of Abies, but the most interesting are _Abies Douglasii_, a very handsome tree only lately introduced, of very quick growth; and the Hemlock Spruce (_Abies canadensis_). This genus is called Pinus by the Linnean botanists, Picea by Professor Link and some German botanists; and Dr. Lindley, who calls it Abies, includes in it the Silver Fir, the Larch, and the Cedar.