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ELEMENTARY SCIENCE MANUALS. BOTANY FOR SCHOOLS AND SCIENCE CLASSES, BY W. J. BROWNE, M.A., Loyn., INSPECTOR OF NATIONAL SCHOOLS. Second Edition, revised and enlarged, Err CM . AUC IERZ «| £05) ERO DUBLIN: SULLIVAN, BROTHERS. LONDON: SIMPKIN, MARSHALL, & CO. a2. . PREFACE. PrrHaPs no other branch of science affords such a combination of instruction and entertainment as that which treats of the structure and varieties of the vegetable kingdom. The materials are everywhere around us, pre- senting in their endless diversity a constant source of novelty and enjoyment. No costly apparatus is required for the study ; a penknife, a pocket-lens, and a very few ,other simple instruments will complete the outfit of the amateur botanist ; and with such aids, and the assiduous employment of his own hands and eyes, he may make considerable progress, In this volume the author has endeavoured to supply a simple introduction to Botany in all its branches. Struc ture, Classification, and Description are treated of in suc- cession, briefly, but it is hoped clearly. To aid the student in his preparation, questions are given at the end of every chapter on Structural Botany, and these are numbered to correspond with the paragraphs of the text. The object of the book will be attained wherever it awakens in the student a desire for a more intimate acquaintance with the plants displayed on every hill-side and along every pathway; and this taste once acquired, the pursuit will be its own reward. — . The present edition has been carefully revised and considerably enlarged. Sets of Questions given by various examining bodies have been ixtroduced, and several new diagrams and a copious Index added. Ennis, March, 1881. CONTENTS. PAGE INTRODUCTION . . ° ° . - |] STRUCTURAL BOTANY AND VEGETABLE PHYSIOLOGY :— I.—GENERAL STRUCTURE OF A FLOWERING PLANT - 5 IJ.—GERMINATION OF BEAN, WHEAT, SPORE OF FERN - 12 II].—VaAscuLaAR AND CELLULAR PLANTS—VARIOUS TISSUES OF PLANTS : : - - . 19 IV.—THE Roor ° : . ° - 25 V.—TuHe Stem - . : : °° 28 VI.—THer Lear ° : ° ° : ° 35 VII.—THE FLOWER . ° ° ° ° 45 VIII.—Tue Fruit anp SEED - - - - 68 CLASSIFICATION :— IX.—CasstFicaTion or Prants - - - 61 CHARACTERS OF THE MOST rmpoRTANT Barrisn NatupnaL ORDERS - - - - - 67 X.—DEscriprion or Pants - - - . 92 EXAMINATION Papers - - ° ° - 99 InpEx - - - : ° - 105 BOTANY. INTRODUCTION. 1. Botany is the science which treats of plants (Bora»n an herb). It comprises several distinct branches, the principal of which are :— Vegetable Morphology, or Structural Botany, which considers the form and structure of plants, and their various parte (nop, form). . Vegetable Physiology, or the mode of life and growth of plants. Systematic Botany, or the arrangement of plants into classes. 2. The Three Kingdoms of Nature. All the objects in the world may be divided into two great groups—living things, and things without life. Bodies without life are called minerals, and form what is called the Mineral Kingdom—such as stones, metals, water. Living bodies are either plants or animals; plants form the Vegetable Kingdom, animals the Animal Kingdom. 3. The parts of which a mineral is composed are usually alike, and independent of one another. But this is not the case with plants or animals; they are composed of diverse or unlike parts, having definite relations to each other. These parts are called organs, and each organ has a certain duty or function to erform. Thus the nose of an animal is an organ, whose nection is smelling ; the eye an organ, whose function is see- ing. Again, the root of a plant is an organ whose function is to take in food; the seed, an organ whose function is to produce a new plant. Animals and plants are called organic or organised bodies, because they possess organs ; minerals are inorganic or unorganised bodies. | 4, Plants and animals differ in many respects, and it is in general easy to know them from each other. It is very easy, B ’ NY. 9 BOTANY for example, to distinguish an elephant from an oak, or a dog from a rose tree. But it is very hard to say whether some of the smaller forms of living matter observed by the microscope are plants or animals. The surest means to distinguish be- tween them is, perlaps, the nature of the food required by them. Plants get their food from the soil and the atmosphere. They take it up in the form of inorganic or mineral matter, as water, carbonic acid gas, and ammonia. These they change into the complex matters of which they are themselves com- posed, such as starch, sugar, &c. Now animals cannot subsist on inorganic matter. They require to have almost the whole of their food in the form of some such compounds as those formed by plants—that is, animals can live only on plants, er on other animals. A cow cannot live on clay; but grows on the clay, and the cow eats the grass and changes it mto beef. The parts of the soil are, therefore, changed from the condition of minerals to that of plants, and thence into that of animals. Thus vegetables form a connecting link be- tween the other two kingdoms; and minerals, vegetables, and animals consist of the same materials, but in different forms. 5. Chemists have discovered that there are altogether about sixty-three different kinds of matter, existing in very small arts called atoms, and collections of atoms, called molecules. en a body contains only one kind of atoms, it is called a simple or elementary body, or an élement—such as iron, gold, charcoal, sulphur. But when a body contains several kinds of atoms, it is called a compound—as chalk, salt, sugar. Although there are only sixty-three elements, the number of compounds formed from these is very great. It has been found, further, that plants are made up chiefly of about sixteen elements. Three of these occur in every vegetable substance—namely, Carbon, Hydrogen, and Oxygen. Carbon is a solid (the same as eharcoal) ; hydrogen and oxygen are gases. In many parts of plants another gas called Nitrogen is found combined with these three elements. The compounds formed from carbon, hydrogen, oxygen, and nitrogen, make up the volatile parts of plants—that is, they pass away when the plants are burned, leaving behind a uantity of ash, which is called the fixed or non-volatile part. he elements found in the ash vary with the nature of the plant ; but the commonest are potassium, sulphur, silicon, fluorine, chlorine, phosphorus, sodium, calcium, magnesium, iron, and manganese; lodine and bromine, also, are found in seaweeds. 6. The elements are denoted for brevity by their initial etters—thus C stands for carbon, H for hydrogen, N for INTRODUCTION. 3 nitrogen, O for oxygen. Also, small figures placed to the right of the letters, and a little lower down, indicate the number of atoms of each element present in a molecule of any compound. Thus water is denoted by OH,, showing that the molecule of water is composed of one atom of oxygen and two atoms of hydrogen. Carbonic acid gas is represented by CO,—that is, one atom of carbon and two atoms of oxygen form one mole- cule of carbonic acid gas. Ammonia consists of one atom of nitrogen united to three atoms of hydrogen, NH;. These are inorganic compounds, taken in as food by plants. The atmo- here consists of two simple gases—oxygen and nitrogen ; but these are merely mixed together, and not combined as in the substances just named, In every 100 parts of air by weight, there are 23 of oxygen, and 77 of nitrogen. The atmo- sphere contains also a quantity of aqueous vapour or steam, and about 4 parts in every 10,000 of carbonic acid gas, (‘04 per cent.) Plants get carbonic acid from the air, but no nitrogen, which is only taken up in its compounds. The other elements and compounds are taken in, when dissolved in water, by the roots o nts. i. From the substances thus absorbed plants manufacture compounds with entirely new properties. The first compound formed by them is called protoplasm, and is composed of car- bon, hydrogen, oxygen, and nitrogen ; and from it all the others are produced by various modifications. The other products of plants are very various. Tle following are a few of the more mportant :— tarch (C,H;,,0,;) is found in the parts of plants not exposed to the air and light, as in roots, tubers, and grain. Cellulose (CsH100;5) forms the walls of young cells, and the basis of all vegetable tissues. It is found nearly pure in hair of cotton. . Sugar exists in sugar-cane, beet, and maple as cane sugar (C,sH»O,) ; in ripe fruits as grape sugar (C,H,,0,); and in celery, manna, &c., as mannite (C,H,,0,). Gums of various kinds (C,,H,,O,,), as gum-arabic, &c. Albuminoids are compounds containing nitrogen, such as the fibrine of wheat, caseine of peas, &c. Theebief compounds found in theash of plants are—potash tsOy, soda (Na,Q), lime (CaO), magnesia (MgO), Silica (Si0*). 4 BOTANY, A Fig. 1.—Ranunculus Auricomus (Wood Buttercup). a, Entire Plant ; 5, Petal, with gland; c, Section of Flower; pv, Achene. GENERAL STRUCTURE OF A FLOWERING PLANT. 5 CHAPTER I. GENERAL STRUCTURE OF A FLOWERING PLANT. 8. Some plants are simple cells or bags some consist of a single row of cells, laid end to end, and fastened together; others, again, are composed of a number of such strings inter- laced together; but most of our common plants consist of g great variety of cells and other simple parts, combined inte various organs. The former are called simple plants, and are said to be of low organisation; the latter are highly-organised. It is desirable to study the highest plants first, because they are most easily obtained, and are by far the most important, and also, because the lower forms will be much more easil examined after the learner has gained some experience wi the higher. 9. To get a clear notion of the general structure of the higher plants, let us take an example known to everyone— a buttercup or crowfoot, represented in the drawing, Fig. } There are various kinds of buttercup; almost any one will serve for our present purpose. Take up a complete buttercup plant from the ground, carefully removing the earth, so as not to injure any part. Observe that it comprises— (1) An underground part, which is white, and consists of numerous fibres tapering towards their extremities, and giving oft thread-like fibrils; these all grow downward, away from the light. — (2.) An aerial ‘part, comprising a long, slender, hollow, branched stem, giving off flat green expansions, called leaves, and also branches, each of which bears at its extremity a bright gold-coloured flower, or else a flower bud. This part grows directly upwards from the ground. Now this uttercup may be taken as a general type of all the higher plants; all have these parts, more or less perfect. The main central portion, comprising the root and the stem, is called the axis; the underground that is, the root—is the descending axis; and the stem is the ascending axis. The parts given off from the axis are called appendages. Thus, united to the central or main portions of the root are many fibres or. branches, called rootlets; united to the stem are branches, leaves, and flowers—these constitute the appendages. Let us take up these organs in order, and see what we can discover about them. § BOTANY. 10. The Root consists of several fibres growing down- wards, and giving off smaller branches. These fibres ter- -minate in fine, soft points. One use of the root is to hold the plant firmly in its place ; but another function is performed by it—through the root the plant obtains the food which it requires from the soil. Each rootlet termi- nates in a little sheath of flattened cells, enveloping the tip, within which is a mass of denser cells, forming the growing oint. Nourishment is taken up, not by the growing point, Put by long delicate cells standing out from the surface of the root-fibres—root-hairs. No solids can pass up in this way ; the food of plants consists entirely of liquids and gases. The root-fibres are spread out like arms through the soil to search for food, and this food, when found, passes up along their interior. Mark that all the root is white; that the root-fibres appear to be given off irregularly ; and that no leaves or buds are given off from any part of it. 11. On taking up the Stem, you observe at once a very marked contrast between it and the root. Except a short, thickened part just under the ground, the stem is green; the leaves also are green, and the flowers a bright yellow. You find nowhere above ground the dull white of the roots. And the same difference appears in all plants; the underground paris are whitish, the parts above ground either green or coloured. If, however, you cover a plant with earth with- out killing it, the stem and even the leaves become white, as in blanched celery and potatoes growing in dark corners. On the other hand, if parts growing underground are ex- posed to the air and light, they may become green, as is seen in potatoes from which the earth has been removed so as to expose the growing tubers. 12. The substance which imparts this green colour to cer- tain parts of plants is called chlorophyll (xAwpbs, green; puddor, a leaf). Itis distributed through the protoplasm in small grains. Whenthe plant is deprived of light, these granules are formed, but want the colouring matter: and the same thing occurs if iron is not contained in the food of the plant. When exposed to sunlight, chlorophyll grains develop starch ; this is dissolved during the night, and either used up in growth, or stored in some reservoir for future use. The green colour of chlorophyll often gives place to yellow or red, as in the ripening of fruits. The other colours of lants do not seem to depend on light; thus flowers have their proper colours as soon as formed, even in the dark. The exact composition of chlorophyll is not known. It plays a very important part in the life of the plant, being GENERAL STRUCTURE OF A FLOWERING PLANT. 7 ‘the principal agent by which it takes from the atiwosphere the carbon required to build up its parts. 13. Pursuing our examination of the stem, we find that it is a long, jointed tube terminating in a flower, and giving of branches which also terminate in flowers. In its earliest stage. it is solid; but as the growth of the stem goes on faster than new matter is formed in the interior, it becomes hollow. The stem consists of soft matter without any wood, and is hence called herbaceous. The outer coating of the stem may be readily stripped off: it is covered with hair or down. This covering is called the epidermis, and, if you examine carefully, you will find the whole plant enveloped in the same covering —all except the cellular sheath at the end of the rootlets, and a single point in the flower. 14. The Leaves. From the base of the stem some leaves spring ; since they appear to come from the root, they are called radical leaves. Each of these radical leaves has a long stalk, which, at its lower extremity, widens so as to sheathe the stem; and the leaves themselves are very deeply divided and sub- divided. Other leaves are given off along the stem, and these, though still much divided, become simpler as we ascend; the stalk also becomes shorter, but still sheathes the stem. From the greatly divided leaves, the whole buttercup family get the name of crowfoots. The flat part of the leaf is called the blade or lamina, the stalk which supports it the leaf-stalk or petiole. The acute angle formed by the petiole with the stem is called the azil of the leaf. In the axils of the leaves there are formed at first buds, from which spring branches bearing flowers. Such buds are called axillary. 15. The leaves are green on the upper surface, somewhat lighter on the under side, and with numerous hairs both above and below. The leaf-stalk is continued through the middle of the leaf, and gives off a branch to each division. Each branch sends off smaller branches, and these still smaller; the whole forming a network or reticulation. If you tear such a leaf, you do not get a straight edge, but a jagged line. The continuation of the petiole through the blade is called the midrib; the parts which it gives off are called sometimes bs, more commonly veins, sometimes nerves. The leaves of the buttercup are said to be net-veined, or the venation is reticulate. 16. All these leaves are called foltage leaves, to distinguish them from floral leaves; those springing from the base of the stem, radical; those connected with the stem proper, cauline. In our buttercup only one leaf is given off from any one part of the stem: the leaves are therefore said to be alternate. In some plants two leaves are given off at the same part of the awa