The Scotch pine.—This is a large tree, with a dome-shaped crown of foliage. The bark is rough and scaly. Its foliage leaves (Fig. 130) are long and needle-shaped, and occur in pairs, each pair being carried by a very short branch. The leaves do not fall off each winter, as do those of most forest trees, but remain on the branches for three years or more, so that the younger twigs are clothed with foliage at all [Pg 162] seasons. The cones of male flowers (Fig. 130, 1, a) are found at the base of some of the shoots of the current year. The female cones (Fig. 130, 1, b) are formed round the ends of the young twigs. They consist mainly of overlapping woody scales, each being knobbed on its exposed surface and bearing a couple of ovules near the base, where it springs from the axis of the cone. The young cones are erect, and in spring (when clouds of pollen are blowing about) their scales separate slightly to admit the pollen in the chinks between them. After pollination the scales close again and the cone hangs down (Fig. 130, 1, c). The ovules receive the pollen in May, but the actual union, or fertilisation, does not take place until June of the following year. The seeds become mature two years after fertilisation. When they are ripe each bears a thin wing which has split off from the upper surface of the scale. The scales now separate, and the winged seeds fall out, to be distributed by the wind. When all the seeds have fallen, the empty cones drop off the tree. Fig. 130.—The Scotch Pine. 1, branch with male (a) and female (b, c) cones; c, cone (× ⅔): 2, two views of a stamen (× 2): 3, scales bearing two ovules (× 2): 4, scale with two seeds (a), wing (b), seed (c): 5, seed in longitudinal section (× 1½). Owing to the length of time necessary for the ripening of the seeds, cones of various ages may be found on the tree all the year round. [Pg 163] The spruce fir.—The spruce has a characteristic conical shape, which is familiar in Christmas trees. The branches are long, and spread horizontally. The foliage leaves are needle-shaped and four-sided in section, but are shorter than those of the pine, and are borne singly. The tree is “evergreen” in the sense that the pine is so, that is, the leaves are not shed all together, but gradually. The method of pollination, fertilisation, and distribution of the winged seeds is similar to that of the pine. In the spruce, however, the seeds are ripe in October of the year in which the cones are pollinated.