Fig. 93.—Branch of the Scotch Pine. magnificent work on this tribe. In its present restricted form, it contains only those plants that have long slender leaves, which are produced in membranaceous sheaths, (see a in fig. 93) two, three, or five together. The male flowers are produced in long upright catkins, (m) growing two or three toge ther, and they consist each of one scale, which is surmounted by a kind of crest, (b). The pollen is contained in two cells formed in the body of each scale, which open lengthways, as shown in the scale of the Scotch Pine (Pinus sylvestris), at (g) in fig. 94. The female scales or carpels when ripe form a strobile or cone (d), and in the Scotch Pine they are thickened at the tip (e in fig. 93); but when young they appear as shown at (f). Each scale is furnished with a thin membrane-like bract on the outside, which is conspicuous when young, but which is hidden by the scales in the ripe cone; and each has two seeds inside, which are each furnished with a long thin transparent wing (c). When the seed is ripe, the cone opens as shown at (d), and the seeds falling out are carried away by the wind. When the seed is sown and begins to germinate, the young plant sends down a root, and pushes through the ground its upright shoot, which has six cotyledons, bearing the husk of the seed upon their tip. All the species of the genus Pinus agree with the Scotch Pine in the construction of their flowers, and they differ from each other principally in their cones, and in the number of leaves which they have in a sheath. By far the greater number have two leaves in a sheath, (see a in fig. 93,) and among these are the Scotch Pine (P. sylvestris), which has small straight cones without prickles; P. Banksiana, which has crooked cones; P. pungens and other American Pines, which have prickly cones, every scale being furnished with a sharp spine; the Corsican Pine (P. Laricio), and several allied species, which have no spines on their cones, but every scale curving outwards; the Pinaster (P. Pinaster) which has large cones, with very short broad spines, and the Stone Pine (P. Pinea), the cones of which are smooth and shining, and very large, and the seeds of which are eaten. The pines that have three leaves in a sheath, are chiefly natives of North America, and have prickly cones; such as Pinus Tæda and its allies, P. ponderosa, remarkable for its heavy wood which sinks in water, and its large spreading branches; and P. Sabni and P. macrocarpa, which have long,
Fig. 95.—Weymouth Pine
(P. strobus). slender, drooping leaves, and very large hooked cones. The pines which have five leaves in a sheath, include, among others, the Weymouth Pine (P. Strobus), the cones of which are long, narrow, and drooping (see fig. 95); P. Lambertiana, which has cones above a foot long; and P. Cembra, which has an oval cone, the scales of which are concave, and the seeds without wings.
THE GENUS ABIES.—THE SPRUCE FIR.
This genus includes all the Spruce Firs, and they are readily distinguished from the pines by
Fig. 96.—Spruce Fir
(Abies excelsa). 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
Fig. 97.—Pinus pumilio. Pinus pumilio, a dwarf variety of the Scotch Pine.