A practical course in botany — Context and Discussion

I. THE STORAGE OF FOOD IN SEEDS 1

II. SOME PHYSIOLOGICAL PROPERTIES OF SEEDS 10

III. TYPES OF SEEDS 12

IV. SEED DISPERSAL 21

CHAPTER II. GERMINATION AND GROWTH

I. PROCESSES ACCOMPANYING GERMINATION 29

II. CONDITIONS OF GERMINATION 33

III. DEVELOPMENT OF THE SEEDLING 40

CHAPTER III. THE ROOT

I. OSMOSIS AND THE ACTION OF THE CELL 53

II. MINERAL NUTRIMENTS ABSORBED BY PLANTS 58

III. STRUCTURE OF THE ROOT 61

IV. THE WORK OF ROOTS 65

V. DIFFERENT FORMS OF ROOTS 72

I. FORMS AND GROWTH OF STEMS 81

II. MODIFICATIONS OF THE STEM 88

B. HERBACEOUS DICOTYLS 102

C. WOODY STEMMED DICOTYLS 107

IV. THE WORK OF STEMS 112

V. WOOD STRUCTURE IN ITS RELATION TO INDUSTRIAL USES 118

CHAPTER V. BUDS AND BRANCHES

I. MODES OF BRANCHING 131

III. THE BRANCHING OF FLOWER STEMS 141

I. THE TYPICAL LEAF AND ITS PARTS 147

II. THE VEINING AND LOBING OF LEAVES 154

III. TRANSPIRATION 160

IV. ANATOMY OF THE LEAF 164

VI. THE LEAF AN ORGAN OF RESPIRATION 174

VII. THE ADJUSTMENT OF LEAVES TO EXTERNAL RELATIONS 177

VIII. MODIFIED LEAVES 189

CHAPTER VII. THE FLOWER

I. DISSECTION OF TYPES WITH SUPERIOR OVARY 196

II. DISSECTION OF TYPES WITH INFERIOR OVARY 204

III. STUDY OF A COMPOSITE FLOWER 210

IV. SPECIALIZED FLOWERS 214

V. FUNCTION AND WORK OF THE FLOWER 219

VI. HYBRIDIZATION 223

VII. PLANT BREEDING 230

VIII. ECOLOGY OF THE FLOWER

A. THE PREVENTION OF SELF-POLLINATION 235

B. WIND POLLINATION 239

C. INSECT POLLINATION 241

D. PROTECTIVE ADAPTATION 245

I. HORTICULTURAL AND BOTANICAL FRUITS 250

II. FLESHY FRUITS 255

IV. ACCESSORY, AGGREGATE, AND MULTIPLE FRUITS 265

CHAPTER IX. THE RESPONSE OF THE PLANT TO ITS SURROUNDINGS

I. ECOLOGICAL FACTORS 271

II. PLANT ASSOCIATIONS 277

III. ZONES OF VEGETATION 288

CHAPTER X. CRYPTOGAMS

I. THEIR PLACE IN NATURE 296

VIII. THE RELATION BETWEEN CRYPTOGAMS AND SEED PLANTS 354

IX. THE COURSE OF PLANT EVOLUTION 359

1. SYSTEMATIC BOTANY 364

2. WEIGHTS, MEASURES, AND TEMPERATURES 367

I. THE STORAGE OF FOOD IN SEEDS

MATERIAL.—In addition to the four food tests described in Exps. 1-6, there should be provided some raw starch, a solution of grape sugar, the white of a hard-boiled egg, and any fatty substance, such as lard or oil. For Exps. 8 and 9, a little diastase solution will be necessary. “Taka” diastase, made from rice acted upon by a fungus, can be obtained for a trifle at almost any drug store.

LIVING MATERIAL.—Grains of corn and wheat, and seeds of some kind of bean, the larger the better. The “horse bean” (_Vicia faba_), if it can be obtained, makes an excellent object for study, as the cells are so large that they can be seen with the naked eye. For showing the presence of proteins (aleurone grains) and oily matter, use thin cross sections through the kernel of a castor bean or a Brazil nut. Specimens for the study of the individual cell will be found in the hairs growing on squash seedlings, in the epidermis of one of the inner coats of an onion, in the roots of oat or radish seedlings, or in the section of a young corn root.

A compound microscope will be required for this study.

=1. The economic importance of seeds.=—As a source of food to both man and the lower animals, the importance of seeds can hardly be overrated. All the flour, meal, rice, hominy, and other breadstuffs sold in the market come from them, to say nothing of the fleece from the cotton seed that clothes the greater part of the world, besides furnishing a substitute for lard and an important food for cattle. The oils and fats stored in nuts are also to be taken into account, the peanut alone yielding the greater part of the so-called olive oil of commerce. Since the value of our farm crops depends largely upon the kind and quantity of these substances furnished by them, it is worth our while, as a matter of economic as well as scientific interest, to learn something about the nature of the different foods contained in plants.