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It's truly remarkable how the great variety of leaves follow a comparatively few fundamental patterns -- "humming one tune to infinite variations," as Emerson says of the unity underlying all things. And what fun it is to learn to know the trees by their leaves and to use these "calling-cards" of theirs for introduction to all the wonders of Treeland! First of all, these leaves fall into two broad divisions. Those that are all in one piece are called "simple," and those in groups "compound." The compound leaves are of two kinds: "pinnate" 1("Pinnate" is from a Latin word "pinna," which means "feather." The leaflets of which this style of compound leaf is composed are arranged on opposite sides of the midrib (although not always opposite each other) as the barbs of a feather are arranged opposite each other on the shaft.) where the leaves are arranged along the stem, as in the Locust; "palmate," where all the leaflets radiate from the top of the midrib, as the fingers radiate from the outspread palm of the hand -- as in the Horse-Chestnut. OUR PICTURE GUIDE TO TREELAND The little leaf artists show many playful fancies in designing the outlines of leaves and in shaping the little scallops or the teeth or the "ears," known in tree language as "lobes." All of which would be of great help in a fascinating game of hid-and-seek in which you would get acquainted with the wonderful people of Treeland; in finding the places in the dictionary and the encyclopaedia that tell about their interesting habits and where they came from originally -- in the beautiful mountains or fertile river-valleys of our own country or from the home-lands of interesting people of foreign countries. These differences in the shapes of leaves would be a great help in identifying them. If it weren't for one thing which these big books seem to have forgotten-and that is this: Leaves haven't got their names on them! Yet you must know the name of your leaf or these books won't tell you a thing about it. They won't say a word until you first say the name -- and that's the very thing you don't know! Isn't it provoking? Then you go to a tree book and it's pretty nearly as bad. The only advantage is that this book is all about trees and you can find what tree your leaf belongs to if you read all the descriptions of leaves -- and can make out what they are talking about. Here is one of these descriptions: "Leaf alternate, obovate-oblong, or oval, unequal at base, doubly serrate, acuminate. Leaves come out of the bud conduplicate. Petioles short; stipules fugacious." (There are 264 such descriptions in a book of 533 pages which lies before me as I write.) Yet, unless you've already studied botany, what does all this mean to you? Absolutely nothing! And, even if you already know these botanical terms, how much better it would be if you could at once turn to a picture that looked like your leaf. A picture of a thing talks plain English that anybody can understand, and that instantly. To be sure, there are over 200 excellent leaf pictures in this tree book I've been talking about, but they are scattered through 500 pages, and you have to take a glance at them all to identify and leaf you may find -- unless, of course, you're lucky enough to find what you are looking for early in the game. The reason you have to do this is that, as in all such books for learned people, the leaves are grouped according to family and not according to form. But who that didn't know already would ever think of looking among the pages about Oaks for information about a leaf that looks so much like that of a Willow as does the leaf of the Willow-Oak? Or among the portraits of the Plane family for information about a leaf that looks so much like that of a Maple as does the Sycamore leaf? But if we had our leaf pictures arranged according to form, regardless of family connections,--in other words a Pictured Index, arranged on the same principle as an alphabetical index, we could at the name of any leaf in which we were interested; and the name, like a magic key, opens all the treasures of information in the wide world of dictionaries, encyclopaedias, tree books, periodicals, and everything! So, with the help of the little girl and of another little girl--my wife--I got up just such a Pictured Index of Treeland for a large number of our trees. We three worked it up together for the benefit of all of us. |
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