Here is such a schedule about Fig. 5. On the left, two words are printed with interrogation-points, which show that they are questions. The word Parts? means, what parts has this leaf? The word Venation? means, what is its venation? The answers to these questions are found by looking at the picture, and they are then written in the schedule as you see. Take a sheet of ruled paper, and make a vertical pencil-mark an inch or two from the left edge; at the left of this mark write the questions, Parts? Venation? Now examine a real leaf, and opposite the question, Parts? write what parts you find. Look again at its venation, and write the answer to this question also. Pin each leaf upon the paper that describes it, and hand the collection to the teacher, to see if you have observed correctly. EXERCISE IV. The Framework and its Parts. THE lines upon the blade of a leaf, shown in Fig. 6, are made by its framework. The spaces between NOTE.-A word of caution is here necessary against mistaking the purpose of this book for that of common botanies. The aim of ordinary botanical teaching is simply to impart to pupils a knowledge of plants. In our schools the ambition of both teacher and pupil is to get something done as quickly as possible that will show proficiency. Hence the early attempts at the classification of plants and the consequent precipitation these lines, which are darkened in Fig. 7, are, in the living leaf, filled with green matter. You know the names of the parts of a leaf, and the two following pictures will show you what to call the different parts of the framework. RIBS.-The stoutest pieces of the framework that begin at the petiole and reach quite across the blade, are called ribs. When there is but one, as in Fig. 8, it is called a midrib. FIG. 8. Veinlets. Vein. Midrib. of the pupil into the complexities of the subject before the simpler portions have been sufficiently mastered. Now, the aim of this book is carefully to guard against such a result. These first observations are made without reference to those combinations of characters by which plants are identified as belonging to a particular order, genus, or species. One of our aims is to learn the elementary facts so thoroughly and FIG. 9. Vein. --Rib. Veinlets. VEINS. The branches of the ribs are called veins. veinlets. EXERCISE V. Feather-veined and Palmate-veined Leaves. IF you have carefully compared a few living leaves with Figs. 8 and 9, you know the difference between ribs and veins. familiarly that we may be prepared to go forward and use them afterward. We first study the parts of plants one after another, on account of what they offer directly to observation. When the characters of leaves, stems, flowers, etc., have become familiar, their relations to each other in different plants, which are usually thrust upon the attention at the outset of study, will come to be seen with little effort. This spontaneous action will be sure to occur as soon as the pupil is prepared for it. All that need be done, therefore, is to keep the elements of the subject before the mind, and to acquire the use of accurate Now, when a leaf has but one rib-a midrib—which gives off veins right and left, like Fig. 10, making it look something like a feather, it is called a featherveined leaf; and when several ribs pass FIG. 10. spread-out fingers branching off from the palm of the hand. If a leaf is net-veined, it will be in one of these two fashions. It will be either feather-veined or palmate-veined. In answering the question Venation in your schedule, you may now state whether the leaf in hand is feather-veined or palmate-veined. You may sometimes be troubled to decide whether a leaf is feather-veined or palmate-veined. Large veins near the base sometimes look very much like ribs. Compare your leaf carefully with the pictures and definitions, and write your opinion in the schedule. You may make mistakes at first, but further observation will enable you to correct them. terms in description, without troubling ourselves about the higher growths of the science. |