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.
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.
The larch.—The larch is a cone-bearer, and a near relative of the pines and firs, but it differs from them in shedding its leaves annually. The leaves are (as is usual in cone-bearing trees) needle-shaped, but they are very thin and they grow in tufts on short alternate spurs. The cones are small and are arranged in a row on the twig. Their scales do not fit so closely together as those of the pine and fir cones. The larch tree has a conical form, but can readily be distinguished from the spruce by its drooping boughs, and absence of leaves in winter.
Gymnosperms.—The pines, firs, and larches are neither dicotyledons nor monocotyledons, but belong to a class of plants which botanists call gymnosperms, in allusion to the fact that their ovules are not enclosed in ovaries, like those of other flowering plants, but are naked. This is the most ancient and primitive group of flowering plants known. In fact they form a connecting link between higher flowering plants and the group to which the ferns and horsetails—which are still more primitive—belong.
EXERCISES ON CHAPTER VIII.
1. What trees are the first to put on leaves in England? Which flower before leafing? Which trees are the latest to come into leaf? When do evergreens, for the most part, change their leaves? (N.F.U.)