Plant hardiness zones for Canada and the United States
Blakeslee, Albert Francis, and Chester Deacon Jarvis. 1939. Trees in Winter: Their Study and Identification. New York: Macmillan.
Palmer, E. Laurence, and H. Seymour Fowler. 1975. Fieldbook of Natural History, 2nd ed. New York: McGraw-Hill.
Weiner, Michael A. 1975. Plant a Tree: A Working Guide to Regreening America. New York: Collier Books.
Zim, Herbert S., and Alexander C. Martin. 1952. Trees: A Guide to Familiar American Trees. Illustrated by Dorothea and Sy Barlowe. A Golden Nature Guide. New York: Simon and Schuster.
Trees to most people are of interest aside from their scientific or utilitarian value. It is surprising to many to learn that only a small proportion of the large number of books on trees have been written primarily from the botanical or utilitarian point of view. The majority view trees as elements in the world of beauty out of doors. The highest expression of an appreciation of this beauty appears in the form of poetry or art. It will accordingly be well to consider trees for a moment from this viewpoint before further discussing their study.
Poetry is not an unintelligible ebullition of enthusiasm for the good, the true, the beautiful. Poetry demands sympathy. Sympathy entails familiarity, knowledge; and knowledge is power in poetry as well as business. . . . Few can have a productive appreciation for poetry, but if we learn to see clearly and with sympathy the natural beauty around us we have learned the foundations upon which poetry is based.
Trees are the most consipicuous living elements in the landscape, especially in winter, and as such must appeal strongly to the student of outdoor life. To the landscape artist they are more than canvas or pigments, for they are themselves the picture which on canvas with his pigments he tries to reproduce. If we study art we are led to visit the museums of art. We learn how in different times and in different countries men have seen and interpreted beauty. Some, fore example, find beauty in the single form, others in groups. The result is as varied as the personality of the artists. Although an advance can be discerned in the method of expression and, by the process of evolution, such guiding principles as simplicity and unity have become generally accepted, still it can be readily seen that art as well as dress has styles. Landscape architecture has undergone a development and is subject to changes like other forms of art.
The landscape is a gallery of art always open. The pictures are many, varied, and ever changing. Trees are the principal figures. They are interesting for their individual beauty and for their effect in harmonious groups. It is for us to find these pictures, to discover what in form or conposition or situation makes them interesting. The student of art does the same for the gallery masterpieces and opens his eyes to new worlds of beauty. We also may have our eyes opened, for the landscape is always with us.
Profitable indeed in this connection will be a study of the landscape artists. In what way do trees appeal to them? What part do trees play in their compositions? Is it the individual tree or trees in groups that interest them most? Is it in the foreground, the background or the middle distance that we find them most frequently represented? What species are preferred? Compare Ruysdael, Corot, Constable and other landscape artists. Are they alike in their preferences?
Claude Monet has given us a wonderful series of pictures of the Thames Bridge in varying moods. We may find for ourselves as interesting a series of even a single tree . . . Along a sloping roadside by a farm house stands a Sugar Maple of some eighty winters. Looked at from east or west the tree is narrow -- perhaps from crowding in its youth by neighbors no longer present. From north or south the crown shows the broad, egg-shaped outline more typical of the species. On the eastern side are several ragged limbs broken some four or five years since by an ice storm that blew in a too heavy load of sleet from the east. On the western side the tree seems perfect. From above on the north its outlines are partially blocked by buildings and obscured by the background of the fields below. From the south it seems to raise its head and shows the limbs clear-cut above the sky line. From a distance it is a conspicuous landmark and always interesting. We can picture the tree from different viewpoints. We can see it in different lights and shadows. We can follow the changes in the background of the picture -- the bare ground, the snow, the green fields; the mists, the rain, the full sunlight, the long shadows and the bright tints at sunset or at dawn. We can watch the changes in the tree itself, can note in winter its type of branching and the fine penciling of its twigs against the sky, in spring the opening of its buds and the rapid growth of flower and leaf, in summer the full foliage, in autumn the rich leaf coloring and the fall of leaf and fruit.
A swing hangs from a spreading lower limb. Children play about it. Robins have built their nests in its branches and here they rear their young. Throughout the long, hot summer days its dense covering of leaves leaves a grateful shade below. To the sleepy child the moonlight casts weird fairy shadows of the limbs upon the bedroom floor and the soft rustle of its leaves lulls him to sleep. Is there great wonder then that in after years this same child holds the old family tree dear -- an inseparable part of his youth? The tree has helped to make the house a home. We have been viewing a tree in its human relations. Such a view may not be botany, but whoever has had a home with a tree, knows that it is life.
Blakeslee and Jarvis 1939:13-18.
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