If the buds are irregularly scattered on the twigs, the lateral buds being as strongly developed as the terminal ones, while, in the spring, as is often the case, certain only of the buds develop into new twigs, the others remaining dormant, then the branches assume that irregular, crooked appearance so characteristic of the Oak. If, on the other hand, all the terminal buds are well developed, and the lateral buds are weaker and more regularly distributed, but farther apart, then the tree grows more rapidly in height than in breadth, and assumes more nearly the character of the Pyramidal Poplar. It will thus be seen that the study of trees in their winter condition is not altogether lacking in interest.
Referring once more, but briefly, to the matter of dormant buds, we recommend the reader not only to observe that some buds do not expand with the others during the spring, but to make them the subject of experiment. Thus, when the Horsechestnut is well in leaf, dormant buds will usually be seen on the sides of the twigs, sheltered by the spreading leaves produced at the tips. Now remove the whole cluster of leaves formed by the terminal bud, together with the bud itself, and the hitherto dormant laterals, under the influence of increased light and warmth, and supplied with sap that is now directed into new channels, will speedily show signs of growth. Similarly, the fruit-gardener will remove the tips of the branches of his fruit trees, which often bear buds that are destined to produce leafy twigs only, and thus encourage the growth of the fruiting buds that are situated lower on the twigs.
Let us now briefly consider the structure of buds and the manner in which they are protected. Most buds are surrounded by brownish scales which are impervious to water, and thus prevent a loss by evaporation at a season when the activity of the roots in absorbing moisture from the soil is suspended. Such loss is still further insured in some cases by a covering of natural varnish. On removing this protective coat we find a dense cluster of closely-packed leaves, variously folded or crumpled in different species, and often, in the centre, a cluster of flowers.
What, then, is the true definition of a bud? It is a young branch, and may give rise to a mature branch bearing foliage leaves only, floral leaves only, or a combination of both. A transverse section of a bud, examined, if necessary, with the aid of the microscope, will show the nature of the branch it was destined to produce; and, in the case of buds which represent, in embryo, branches bearing flowers, or both leaves and flowers, it is often an easy matter to see the whorls of the future flowers, and even the pollen cells in the anthers and the ovules in the ovary.
Trees in Winter or Early Spring
5. Birch, with catkins. 6. Poplar. 7. Beech. 8. Alder, with catkins and the old fruit 'cones' of the previous season.
Interesting as it is to study the structure of buds in their dormant condition during winter and early spring, even more fascinating is the watching of the gradual expansion of the bud and the unfolding of the young leaves. And it is not always necessary to make frequent visits to the woods in order to carry out such observations, for a large number of buds will develop almost equally well, at any rate through their earlier stages, if the twigs bearing them be placed in vessels of water either in or out of doors; and in many cases all the stages from dormant bud to perfect leaves and fully-expanded flowers may be watched in this way.