A thorough knowledge of the plants at one's disposal, and their characteristics, will be indispensable in suggesting means of accent to the designer when he is considering horticultural accents. As a rule, the nature of the accent is first considered in the abstract. For instance, a scheme might require an accent plant which should be tall, slender, and of rough texture, with a general red tone. So much decided upon, it is then a question of choosing from the plant materials at one's disposal the variety which will come nearest to satisfying those requirements.
Since the use of line differs markedly in the two schools, it results that in the formal style any change of line, however slight, will immediately affect the areas in their integral relations. Every walk and plat or parterre is bounded by a definite, hard dividing-line, and those lines are the constructive framework of the design, because they are always placed with definite relation to axes.
As the entire design may be seen at a glance in formal work, it follows that the mere altering of the width of a walk will change the proportions of the bordering area, and the divisional proportions will hence assume an entirely different appearance. Consequently, where an example of the formal type has been successfully carried out, it should appear so complete and exact as not to permit of any change in the shape of the planting areas or the width of the walks.
Figure 12. RHODODENDRONS IN THE SARGENT GARDEN, HOLM LEA, BROOKLINE, MASS..
In the informal type considerable changes of outline may be made without materially altering the general appearance. In Figure 13 the arrangement of units is entirely dissimilar, and yet the appearance in elevation would not vary much. The charm of informal planting is closely bound up in the silhouette of its elevation from all different points of view; therefore the outline of the plan of the planting masses seldom attracts much attention. Accordingly the width of planting areas in informal design may often be considerably changed, when necessary, without affecting the general scale.
The irregular boundaries of informal shrubbery masses may easily be altered even to the extent of moving them several feet to give greater freedom of approach, or for some other utilitarian purpose, without causing any marked change of appearance in the masses themselves.
The formal type, where the whole garden scheme is perceived at a glance, is successful or not chiefly on account of its plan, but the strength of the informal type lies largely in elevation.
Since the final result of every design must be a balance, the whole process of designing is toward this end. The balance is either very regular and striking-understood at a glance, as in a geometrical figure-or it may be more a matter of gradual appreciation, as in a Japanese print.
Figure 13. THREE PLANS TO ILLUSTRATE THE FLEXIBLE CHARACTER OF INFORMAL PLANTING MASSES.
These two types of balance, the obvious or symmetrical, and the occult or unsymmetrical, are illustrated respectively by the formal and informal schools (Fig. 14), and the balances are perceptible both in plan and elevation. Formal arrangements are generally geometrical, simple and symmetrical, so far as the structural lines are concerned, while the informal are more complex, irregular, and seldom in the least symmetrical. Formal arrangements are generally in pairs,-that is, are bilaterally symmetrical,-while no exact similarity will appear in an informal one. The general primness imposed by geometrical figures is exactly in keeping with the spirit of a formal garden, but is quite at variance with an informal scheme, the charm of which lies often in a sort of waywardness.
It must be remembered that informal design depends upon details and is generally seen in parts; it may consequently consist of a number of more or less independent balances which should of course appear complete, though none of them will be symmetrical. The formal scheme, presenting one large and very obvious balance, may be seen in its entirety at a glance.
All design is based upon repetition, and all design is consequently similar in so far as its appearance is affected by the laws of repetition. The diversity of the materials employed to express the laws of repetition in different forms of design is that which confuses the beginner.
The laws of repetition may be divided into three principal parts: sequence or simple repetition, rhythm, and balance.
A design should first of all possess unity; that is to say, it should "hang together," and not appear as a jumble of separate parts. This necessitates at the outset a certain amount of repetition, and in consequence it is necessary that some one element be common to all parts of the design. Of course, if too many elements are possessed in common, there will be no variety, and the result will be perfectly monotonous. Repetition applies to the forms, sizes, colors, and positions of all materials used (Fig. 15).
It is not necessary that plant materials should be alike in all respects, but only that more of their characteristics should be alike than not, in order to secure conditions of sufficient monotony to produce an appearance of quiet and rest.
Figure 14. 1NFORMAL AND FORMAL BALANCES.