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Experiment.—Get together some slices of white potato, sweet potato, parsnip, broken kernels of corn, wheat and oats, a piece of laundry starch and some tincture of iodine diluted to about the color of weak tea. Rub a few drops of the iodine on the cut surfaces of the potatoes, parsnip, and the broken surfaces of the grains. Notice that it turns them purple. Now drop a drop of the iodine on the laundry starch. It turns that purple also. This experiment tells us that plants contain starch.
Experiment.—Chew a piece of sorghum cane, sugar cane, cornstalk, beet root, turnip root, apple or cabbage. They all taste sweet and must therefore contain sugar.
Examine a number of peach and cherry trees. You will find on the trunk and branches more or less of a sticky substance called gum.
Experiment.—Crush on paper seeds of cotton, castor-oil bean, peanuts, Brazil nuts, hickory nuts, butternuts, etc. They make grease spots; they contain fat and oil.
Experiment.—Chew whole grains of wheat and find a gummy mucilaginous substance called wheat gum, or wet a pint of wheat flour to a stiff dough, let it stand about an hour, and then wash the starch out of it by kneading it under a stream of running water or in a pan of water, changing the water frequently. The result will be a tough, yellowish gray, elastic mass called gluten. This is the same as the wheat gum and is called an albuminoid because it contains nitrogen and is like albumen, a substance like the white of an egg.
If we crush or grate some potatoes or cabbage leaves to a pulp and separate the juice, then heat the clear juice, a substance will separate in a flaky form and settle to the bottom of the liquid. This is vegetable albumen.
Experiment.—Crush the leaves or stems of several growing plants and notice that the crushed and exposed parts are moist. In a potato or an apple we find a great deal of moisture. Plants then are partly made of water. In fact growing plants are from 65 to 95 per cent. water.
Experiment.—Expose a plant or part of a plant to heat; the water is driven off and there remains a dry portion. Heat the dry part to a high degree and it burns; part passes into the air as smoke and part remains behind as ashes.
We have found then the following substances in plants: Woody fibre or cellulose, starch, sugar, gum, fats and oils, albuminoids, water, ashes. Aside from these are found certain coloring matters, certain acids and other matters which give taste, flavor, and poisonous qualities to fruits and vegetables. More or less of all these substances are found in all plants. Now these are all compound substances. That is, they can all be broken down into simpler substances, and with the exception of the water and the ashes, the plants do not take them directly from the soil.
The chemists tell us that these substances are composed of certain chemical elements, some of which the plant obtains from the air, some from the soil and some from water.
The following table gives the substances found in plants, the elements of which they are composed, and the sources from which the plants obtain them:
+ Substances found Elements of which Sources from in plants. they are made. which plants obtain them. -+ -+ + Cellulose or woody fibre Carbon Air Starch -+ + Sugar Gum Oxygen Water Fat and Oil Hydrogen -+ -+ + Carbon Air + -+ + Albuminoids Oxygen Water Hydrogen + -+ + Nitrogen Sulphur Phosphorus -+ - Soil + Phosphorus Potassium Ashes Calcium Magnesium Iron -+ -+ + Water Oxygen Soil Hydrogen -+ +
Here is a brief description of these chemical elements.
Oxygen, a colorless gas, forms one-fifth of the air.
Hydrogen, a colorless gas, forms a part of water.
Carbon, a dark solid, forms nearly one-half of all organic matter; charcoal is one of its forms. The lead in your pencil is another example.
Nitrogen, a colorless gas, forms four-fifths of the air. Found in all albuminoids.
Sulphur, a yellow solid.
Phosphorus, a yellowish white solid.
Potassium, a silver white solid.
Calcium, a yellowish solid. Found in limestone.
Magnesium, a silver white solid.
Iron, a silver gray solid.
Of these elements the nitrogen, sulphur, phosphorus, potassium, calcium, magnesium, and iron must not only exist in the soil but must also be there in such form that the plant can use them. The plant does not use them in their simple elementary form but in various compounds. These compounds must be soluble in water or in weak acids.
Of these seven elements of plant food the nitrogen, phosphorus, and potassium and calcium are of particular importance to the farmer, because they do not always exist in the soil in sufficient available quantities to produce profitable crops. Professor Roberts, of Cornell University, tells us that an average acre of soil eight inches deep contains three thousand pounds of nitrogen. The nitrogen exists largely in the humus of the soil and it is only as the humus decays that the nitrogen is made available. Here is another reason for keeping the soil well supplied with organic matter. The decay of this organic matter is hastened by working the soil; therefore good tillage helps to supply the plant with nitrogen.
If the nitrogen becomes available when there is no crop on the soil it will be washed out by rains and so lost. Therefore the soil, especially if it is sandy, should be covered with a crop the year through. Many lands lose large amounts of plant food by being left bare through the fall and winter, especially in those parts of the country where the land does not freeze. The phosphorus, potassium and calcium also exist in most soils in considerable quantities, but often are not available; thorough tillage and the addition of organic matter will help to make them available, and new supplies may be added in the form of fertilizers. Calcium is found in nearly all soils in sufficient quantities for most crops, but sometimes there is not enough of it for such crops as clover, cowpea, alfalfa, etc. It is also used to improve soil texture. The entire subject of commercial fertilizers is based almost entirely on the fact of the lack of these four elements in the soil in sufficient available quantities to grow profitable crops. The plant gets its phosphorus from phosphoric acid, its potassium from potash, and its calcium from lime.
There is a class of plants which have the power of taking free nitrogen from the air. These are the leguminous plants; such as clover, beans, cowpeas, alfalfa, soy bean, etc. They do it through the acid of microscopic organisms called bacteria which live in nodules or tubercles on the roots of these plants (Figs. 34-35). Collect roots of these plants and find the nodules on them. The bacteria take nitrogen from the air which penetrates the soil and give it over to the plants. Here is another reason for good soil ventilation.
This last fact brings us to another very important property of soils. Soils have existing in them many very small plants called bacteria. They are so very small that it would take several hundred of them to reach across the edge of this sheet of paper. We cannot see them with the naked eye but only with the most powerful microscopes. Some of these minute plants are great friends to the farmer, for it is largely through their work that food is made available for the higher plants. Some of them break down the organic matter and help prepare the nitrogen for the larger plants. Others help the leguminous plants to feed on the nitrogen of the air. To do their work they need warmth, moisture, air, and some mineral food; these conditions we bring about by improving the texture of the soil by means of thorough tillage and the use of organic matter.
CHAPTER IX
SEEDS
CONDITIONS NECESSARY FOR SEEDS TO SPROUT
In the spring comes the great seed-planting time on the farm, in the home garden and in the school garden. Many times the questions will be asked: Why didn't those seeds come up? How shall I plant seeds so as to help them sprout easily and grow into strong plants? To answer these questions, perform a few experiments with seeds, and thus find out what conditions are necessary for seeds to sprout, or germinate. For these experiments you will need a few teacups, glass tumblers or tin cans, such as tomato cans or baking-powder cans; a few plates, either of tin or crockery; some wide-mouth bottles that will hold about half a pint, such as pickle, olive, or yeast bottles or druggists' wide-mouth prescription bottles; and a few pieces of cloth. Also seeds of corn, garden peas and beans.
Experiment.—Put seeds of corn, garden peas, and beans (about a handful of each) to soak in bottles or tumblers of water. Next day, two hours earlier in the day, put a duplicate lot of seeds to soak. When this second lot of seeds has soaked two hours, you will have two lots of soaked seeds of each kind, one of which has soaked twenty-four hours and the other two hours. Now take these seeds from the water and dry the surplus water from them by gently patting or rubbing a few at a time in the folds of a piece of cloth, taking care not to break the skin or outer coating of the seed. Place them in dry bottles, putting in enough to cover the bottoms of the bottles about three seeds deep; cork the bottles. If you cannot find corks, tie paper over the mouths of the bottles. Label the bottles "Seeds soaked 24 hours," "Seeds soaked 2 hours," and let them stand in a warm place several days. If there is danger of freezing at night, the bottles of seeds may be kept in the kitchen or living room where it is warm, until they sprout.
Observe the seeds from day to day. The seeds that soaked twenty-four hours will sprout readily (Fig. 36), while most, if not all, of those that soaked only two hours will not sprout. Why is this? It is because the two-hour soaked seeds do not receive sufficient moisture to carry on the process of sprouting.
Our experiment teaches us that seeds will not sprout until they receive enough moisture to soak them through and through.
This also teaches that when we plant seeds we must so prepare the soil for them and so plant them that they will be able to get sufficient moisture to sprout.
Experiment.—Soak some beans, peas or corn, twenty-four hours; carefully dry them with a cloth. In one half-pint bottle place enough of them to cover the bottom of the bottle two or three seeds deep; mark this bottle A. Fill another bottle two-thirds full of them and mark the bottle B (Fig. 37). Cork the bottles and let them stand for several days. Also let some seeds remain soaking in the water. The few seeds in bottle A will sprout, while, the larger number in bottle B will not sprout, or will produce only very short sprouts. Why do not the seeds sprout easily in the bottle which is more than half full?
To answer this question try the following experiment:
Experiment.—Carefully loosen the cork in bottle B (the bottle containing poorly sprouted seeds), light a match, remove the cork from the bottle and introduce the lighted match. The match will stop burning as soon as it is held in the bottle, because there is no fresh air in the bottle to keep the match burning. Test bottle A in the same way. What has become of the fresh air that was in the bottles when the seeds were put in them? The seeds have taken something from it and have left bad air in its place; they need fresh air to help them sprout, but they have not sprouted so well in bottle B because there was not fresh air enough for so many seeds. The seeds in the water do not sprout because there is not enough air in the water. Now try another experiment.
Experiment.—Fill some tumblers or teacups or tin cans with wet sand and others with clay that has been wet and then thoroughly stirred till it is about the consistency of cake batter or fresh mixed mortar. Take a tumbler of the wet sand and one of the wet clay and plant two or three kernels of corn in each, pressing the kernels down one-half or three-quarters of an inch below the surface; cover the seeds and carefully smooth the surface. In other tumblers plant peas, beans, and other seeds. Cover the tumblers with saucers, or pieces of glass or board to keep the soil from drying. Watch them for several days. If the clay tends to dry and crack, moisten it, fill the cracks and smooth the surface. The seeds in the sand will sprout but those in the clay will not (see Fig. 38). Why is this? Water fills the small spaces between the particles of clay and shuts out the fresh air which is necessary for the sprouting of the seeds.
This teaches us that when we plant seeds we must so prepare the soil, and so plant the seeds that they will get enough fresh air to enable them to sprout, or, in other words, the soil must be well ventilated.
Experiment.—Plant seeds of corn and beans in each of two tumblers; set one out of doors in a cold place and keep the other in a warm place in the house. The seeds kept in the house will sprout quickly but those outside in the cold will not sprout at all. This shows us that seeds will not sprout without heat.
If the weather is warm place one of the tumblers in a refrigerator.
Why don't we plant corn in December?
Why not plant melons in January?
Why not plant cotton in November?
The seeds of farm crops may be divided into two classes according to the temperatures at which they will germinate or sprout readily and can be safely planted.
Class A. Those seeds that will germinate or sprout at an average temperature of forty-five degrees in the shade, or at about the time the peach and plum trees blossom:
Barley Beet Parsley Oats Carrot Parsnip Rye Cabbage Onion Wheat Cauliflower Pea Red Clover Endive Radish Crimson Clover Kale Turnip Grasses Lettuce Spinach
These can be planted with safety in the spring as soon as the ground can be prepared, and some of them, if planted in the fall, live through the winter.
Class B. Those seeds that will germinate or sprout at an average temperature of sixty degrees in the shade, or when the apple trees blossom:
Alfalfa Soy Bean Squash Cow Pea Pole Bean Cucumber Corn String Bean Pumpkin Cotton Melon Tomato Egg Plant Okra Pepper
We are now ready to answer the question: What conditions are necessary for seeds to sprout or germinate? These conditions are:
The presence of enough moisture to keep the seed thoroughly soaked.
The presence of fresh air.
The presence of more or less heat.
This teaches us that when we plant seeds in the window box or in the garden or on the farm we must so prepare the soil and so plant the seeds that they will be able to obtain sufficient moisture, heat, and air for sprouting. The moisture must be film water, for if it is free water or capillary water filling the soil pores, there can be no ventilation and, therefore, no sprouting.
SEED TESTING
In a previous experiment (page 73) the seeds planted in the wet clay did not sprout (see Fig. 38). In answer to the question, "Why is this?" some will say the seeds were bad. It often happens on the farm that the seeds do not sprout well and the farmer accuses the seedsman of selling him poor seed, but does not think that he himself may be the cause of the failure by not putting the seeds under the proper conditions for sprouting. How can we tell whether or not our seeds will sprout if properly planted? We can test them by putting a number of seeds from each package under proper conditions of moisture, heat and air, as follows:
For large seeds take two plates (see Fig. 39) and a piece of cloth as wide as the bottom of the plate and twice as long. Count out fifty or one hundred seeds from a package, wet the cloth and wring it out. Place one end of the cloth on the plate, place the seeds on the cloth and fold the other end of the cloth over them. On a slip of paper mark the number of seeds and date, and place on the edge of the plate. Now cover the whole with another plate, or with a pane of glass to keep from drying. Set the plate of seeds in a warm room and examine occasionally for several days. If the cloth tends to dry, moisten it from time to time. As the seeds sprout take them out and keep a record of them. Or leave them in the plate and after four or five days count those that have sprouted. This will give the proportion of good seeds in the packages.
For small seeds fold the cloth first and place the seeds on top of it.
Another good tester for small seeds is made by running about an inch of freshly mixed plaster of Paris into a small dish or pan and moulding flat cavities in the surface by setting bottles into it. The dish or pan and bottles should be slightly greased to prevent the plaster sticking to them. When the cast has hardened it should be turned out of the mould and set in a large dish or pan. One hundred small seeds are then counted out and put into one of the cavities, others are put into the other cavities. Water is then poured into the pan till it rises half way up the side of the plaster cast or porous saucer. The whole thing is then covered to keep in the moisture (Fig. 40).
Another method is to get boxes of finely pulverized sand or soil and carefully plant in it fifty or one hundred seeds of each kind to be tested. Then by counting those that come up, the proportion of good seeds can easily be found.
In every case the testers should be kept at a temperature of about seventy degrees or about that of the living room.
HOW THE SEEDS COME UP
Plant a few seeds of corn, beans and garden peas in boxes or tumblers each day for several days in succession. Then put seeds of corn, beans and garden peas to soak. After these have soaked a few hours, examine them to find out how the seed is constructed. Note first the general shape of the seeds and the scar (Fig. 41-4) on one side as in the bean or pea and at one end or on one edge in the corn. This scar, also called hilum, is where the seed was attached to the seed vessel.
Cut into the bean and pea, they will be found to be protected by a tough skin or coat. Within this the contents of the seed are divided into two bodies of equal size lying close to each other and called seed leaves or cotyledons (Fig. 41-5). Between them near one end or one side will be found a pair of very small white leaves and a little round pointed projection. The part bearing the tiny leaves was formerly, and is sometimes now, called the plumule, but is generally called the epicotyl, because it grows above or upon the cotyledons. The round pointed projection was formerly called the radicle, but is now spoken of as the hypocotyl, because it grows below or under the cotyledons.
Examine a dry kernel of corn and notice that on one side there is a slight oval-shaped depression (Fig. 41-1). Now take a soaked kernel and cut it in two pieces making the cut lengthwise from the top of the kernel through the centre of the oval depression and examine the cut surface. A more or less triangular-shaped body will be found on the concave side of the kernel (see Figs. 41-2 and 41-3). This is the one cotyledon of the corn. Besides this will be found quite a mass of starchy material packed in the coverings of the kernel and in close contact with one side of the cotyledon. This is sometimes called the endosperm.
Within the cotyledon will be found a little growing shoot pointed toward the top of the kernel. This is the epicotyl, and another growing tip pointed toward the lower end of the kernel; this is the hypocotyl or the part which penetrates the soil and forms roots.
Now examine the seeds that were planted in succession. Some will be just starting a growing point down into the soil. Some of them have probably come up and others are at intermediate stages.
How did the bean get up?
After sending down a root the hypocotyl began to develop into a strong stem which crooked itself until it reached the surface of the soil and then pulled the cotyledons or seed-leaves after it (Fig. 42). These turn green and after a time shrink and fall off.
The pea cotyledons were left down in the soil, the epicotyl alone pushing up to the surface. The corn pushed a slender growing point to the surface leaving the cotyledon and endosperm behind in the soil but still attached to the little plant (Fig. 43).
USE OF COTYLEDONS AND ENDOSPERM
Experiment.—Plant some beans in a pot or box of soil and as soon as they come up cut the seed-leaves from some of them and watch their growth for several days. It will soon be seen that the plants on which the seed-leaves were left increase in size much more rapidly than those from which the seed-leaves were removed (see Figs. 43 and 44). Sprout some corn in the seed tester. When the seedlings are two or three inches long, get a wide-mouthed bottle or a tumbler of water and a piece of pasteboard large enough to cover the top. Cut a slit about an eighth of an inch wide from the margin to the centre of the pasteboard disk. Take one of the seedlings, insert it in the slit, with the kernel under the pasteboard so that it just touches the water. Take another seedling of the same size, carefully remove the kernel from it without injuring the root, and place this seedling in the slit beside the first one (Fig. 45). Watch the growth of these two seedlings for a few days. Repeat this with sprouted peas. In each case it will be found that the removal of the seed-leaves or the kernel checks the growth of the seedling. Therefore, it must be that the seed-leaves which appear above ground, as in the case of the bean, or the kernel of the corn which remains below the surface of the soil, furnish the little plant with food until its roots have grown strong enough to take sufficient food from the soil.
CHAPTER X
SEED PLANTING
HOW DEEP SHOULD SEEDS BE PLANTED?
Experiment.—Plant several kernels of corn in moist soil in a glass tumbler or jar. Put one kernel at the bottom and against the side of the glass, place the next one a half inch or an inch higher and an inch and a half to one side of the first seed and against the glass. Continue this till the top of the glass is reached (Fig. 2). Leave the last seed not more than one-fourth inch below the top of the soil. The soil should be moist at the start and the seeds should all be against the glass so they can be seen. This can best be done by planting as you fill the glass with soil. Plant peas and beans in the same way. Do not water the soil after planting. Set aside in a warm place and wait for the seeds to come up.
Another method of performing this experiment is to make a box having one side glass (Fig. 46). The length and the depth of the box will depend upon the size of the glass you use. Fill the box nearly full of moist soil and plant seeds of corn and beans and peas at depths of one-quarter inch, one inch, two inches, three inches, and four inches. These seeds can best be put in as the box is being filled. Hold each individual seed against the glass with a stick so that when planted they may be seen through the glass. Protect the seeds and roots from light by using a sheet of cardboard, tin or wrapping paper or a piece of board, and set in a warm place.
Many of the seeds planted only one-quarter inch deep will not sprout because the soil about them will probably dry out before they take from it enough moisture to sprout. The one and two-inch deep seeds will probably come up all right. Of the three and four-inch deep seeds, the corn and peas will probably make their way to the surface because they send up only a slender shoot, which can easily force its way through the soil. The deep-planted beans will make a strong effort but will not succeed in forcing their way to the surface because they are not able to lift the large seed-leaves through so much soil, and will finally give up the struggle. If any of the deeper beans do get up, the seed-leaves will probably be broken off and the little plant will starve and be dwarfed. This experiment teaches us that we should plant seeds deep enough to get sufficient moisture for sprouting and yet not so deep that the young seedlings will not be able to force their way to the surface.
Seeds which raise their cotyledons above the soil should not be planted as deep as those which do not. Large, strong seeds like corn, peas, etc., which do not lift their cotyledons above the surface, can be planted with safety at a depth of from one to four or five inches.
Seeds of carrot, celery, parsley, parsnip and egg plant are weak and rather slow in germinating. It is customary to plant them rather thickly in order that by the united strength of many seeds they may more readily come to the surface. This point should be observed also in planting seeds in heavy ground that is liable to pack and crust over before the seeds germinate.
Seed should always be sown in freshly stirred soil and may be planted by hand or with a machine.
For the home garden and the school garden, and when only small quantities of any one variety are planted, a machine is hardly desirable and hand planting is preferable.
The rows are marked out with the garden marker, or the end of a hoe or rake handle (Fig. 47), using a line or the edge of a board as a guide. The seeds are then carefully and evenly dropped in the mark or furrow.
The covering is done with the hand or a rake or hoe, and the soil is pressed over the seeds by patting it with the covering tool or walking on the row and pressing it with the feet. This pressing of the soil over the seeds is to bring the particles of soil close to each other and to the seed so that film water can climb upon them and moisten the seed sufficiently for sprouting.
A convenient way of distributing small seeds like those of turnip and cabbage, is to take a small pasteboard box or tin spice or baking-powder box, and punch a small hole in the bottom near one end or side. Through this the seeds can be sifted quite evenly.
For the larger operations of the farm and market garden, hand and horse-power drills and broadcasters are generally used, though some farmers still plant large fields by hand.
The grasses and clovers are generally broadcasted by hand or machine, and are then lightly harrowed and are generally rolled.
The small grains (wheat, oats, etc.) are broadcasted by many farmers, but drilling is considered better. With the grain drill the seed is deposited at a uniform depth and at regular intervals. In broadcasting, some of the seeds are planted too deep, and some too shallow, and others are left on the surface of the soil.
From experiment it has been found that there is a loss of about one-fifth of the seed when broadcasted as compared with drilling.
As in the case of grass seed, the grains are generally rolled after sowing.
Corn is planted by hand, or by hand- and horse-corn-planters, which drop a certain number of seeds at any required distance in the row.
There are a number of seed drills made for planting vegetable seeds which are good machines.
The main points to be considered in seed drills or seed planting machines are:
Simplicity and durability of structure.
Ease of draft.
Uniformity in quantity of seed planted, and in the distances apart and depth to which they are planted.
The distances apart at which seeds are planted vary according to the character of the plant. Bushy, spreading plants and tall plants require more room than low and slender-growing plants.
Visit the neighboring hardware stores and farms and examine as many seed-growing tools as possible to see how they are constructed and how properly used. Practice planting with these tools, if possible.
Illustrations of grain drills and other seed-planting machines will be found in seed catalogues, hardware catalogues, and in the advertising columns of agricultural papers.
SEED CLASSIFICATION
In order to become familiar with the farm and garden seeds, obtain samples of as many of them as possible. Put them in small bottles—homoeopathic vials for instance—or stick a few of each kind on squares of cardboard. Arrange them in groups according to resemblances or relationships, comparing not only the seeds but the plants on which they grew. If you cannot recall the plants, and there is no collection available, study the illustrations in seed catalogues which can be obtained from seedsmen. The following groups contain most of the farm and garden seeds, excepting flower seeds:
GRASS FAMILY: MUSTARD FAMILY: NIGHTSHADE FAMILY: Corn, Mustard, Potato, Wheat, Cabbage, Tomato, Oats, Cauliflower, Egg Plant, Rye, Collards, Pepper. Barley, Brussels Sprouts, Sorghum, Kale, GOOSEFOOT FAMILY: Orchard Grass, Kohl Rabi, Beet, Red Top Grass, Radish, Chard, Timothy, Ruta Baga, Spinach, Kentucky Blue Grass. Turnips, Mangle Wurzel. Watercress. GOURD FAMILY: PEA OR LEGUME FAMILY: Canteloupe, THISTLE FAMILY: Garden Pea, Citron, Artichoke, Canada Field Pea, Cucumber, Cardoon, Cow Pea, Gourd, Chicory, Soy Bean, Muskmelon, Dandelion, Bush Bean, Pumpkin, Endive, Lima Bean, Squash, Lettuce, Velvet Bean, Watermelon, Salsify, Vetch, Cymling. Sunflower, Clover, Tansy. Alfalfa. PARSLEY FAMILY: Caraway, LILY FAMILY: MALLOW FAMILY: Carrot, Asparagus, Okra, Celery, Garlic, Cotton. Coriander, Leek, Cumin, Onion. Fennel, Parsley, Parsnip.
TRANSPLANTING
The seeds of some crops—cabbage, tomato, lettuce, for example—are planted in window boxes, hot-beds, cold frames or a corner of the field or garden. When the seedlings have developed three or four leaves or have become large enough to crowd one another, they are thinned out or are transplanted into other boxes, frames or plots of ground, or are transplanted into the field or garden.
The time and method of transplanting depend largely on
The condition of the plant.
The condition of the soil.
The condition of the atmosphere.
For best results in field planting the plant should be well grown, strong and stocky, with well developed roots and three or four strong leaves.
The soil should be thoroughly prepared, moist and freshly stirred. A moist day just before a light shower is the best time. These conditions being present, the plants are carefully lifted from the seed bed with as little disturbance of the roots as possible and carried to the field or garden. Some plants, like cabbage, will stand considerable rough treatment, while others, like the eggplant, require greater care.
In the field or garden a hole is made for each plant with the hand, a stick or dibber or any convenient tool, the roots of the plant are carefully placed in it and the soil is pressed about them. If the soil is moist and freshly stirred, new roots will generally start in a very short time.
Plants that have been grown in pots, small boxes or tin cans, as tomatoes and eggplants are sometimes grown, may be quickly transplanted in the field in the following manner: Open the furrow with a small plow, knock the plants out of the pots or cans and place them along the land side of the furrow at the proper distances, then turn the soil back against them with the plow.
When there is a large number of plants to be set, as in planting cabbage, sweet potatoes, etc., by the acre, it is not always convenient to wait for a cloudy day or to defer operations till the sun is low in the afternoon. In such cases the roots of the plants should be dipped in water or in thin mud just before setting them, or a little water may be poured into each hole as the plant is put in. The soil should always be well firmed about the roots. The firming of the soil about the roots of a newly set plant is as important as firming it over planted seeds. The soil should be packed so tightly that the individual leaves will be torn off when an attempt is made to pull the plant up by them.
In dry or warm weather it is a good plan to trim the tops of plants when setting them. This can be done readily with some plants, such as cabbage and lettuce, by taking a bundle of them in one hand and with the other twisting off about half of their tops.
The proper time to transplant fruit and ornamental trees and shrubs is during the fall, winter and early spring, which is their dormant or resting season, as this gives the injured roots a chance to recover and start new rootlets before the foliage of the plant makes demands on them for food and moisture.
In taking up large plants many roots are broken or crushed. These broken and injured roots should be trimmed off with a smooth cut. The tree or shrub is then placed in the hole prepared for it and the soil carefully filled in and packed about the roots. After the plant is set, the top should be trimmed back to correspond with the loss of root. If the plant is not trimmed, more shoots and leaves will start into growth than the damaged roots can properly furnish with food and water, and the plant will make a weak growth or die.
There are on the market a number of hand transplanting machines which, from their lack of perfection, have not come into general use. Many of them require more time to operate than is consumed in hand planting. A number of large machines for transplanting are in successful and satisfactory use on large truck and tobacco farms. These machines are drawn by horses and carry water for watering each plant as it is set.
Practice transplanting in window boxes or in the open soil and see how many of your plants will survive the operation.
CHAPTER XI
SPADING AND PLOWING
We have learned the important conditions necessary for the sprouting of seeds and for the growth and development of roots. We have also learned something about the soil, its properties, and its relation to, or its behavior toward these important conditions. We are therefore prepared to discuss intelligently methods of treating the soil to bring about, or maintain, these conditions.
SPADING THE SOIL
The typical tool for preparing the soil for root growth is a spade or spading fork (Fig. 49). With this tool properly used we can prepare the soil for a crop better than with any other.
In spading, the spade or fork should be pushed into the soil with the foot the full length of the blade and nearly straight down. The handle is then pulled back and the spadeful of earth is pried loose, lifted slightly, thrown a little forward, and at the same time turned. The lumps are then broken by striking them with the blade or teeth of the tool. All weeds and trash should be covered during the operation. A common fault of beginners is to put the spade in the soil on a slant and only about half the length of the blade, and then flop the soil over in the hole from which it came, often covering the edge of the unspaded soil. The good spader works from side to side across his piece of ground, keeping a narrow trench or furrow between the spaded and unspaded soil, into which weeds and trash and manure may be drawn and thoroughly covered, and also to prevent covering the unspaded soil. If this work has been well done with the ordinary spade or fork and finished with a rake, the result will be a bed of soil twelve to fifteen inches deep, fine and mellow and well prepared for root penetration, for good ventilation, for the absorbing and holding of moisture and warmth.
This method should always be employed for small gardens and flower beds.
PLOWING
For preparing large areas of soil the plow is the tool most generally used.
WHY DO WE SPADE AND PLOW?
To break and pulverize the soil and make it soft and mellow, so the roots of plants may enter it in search of food, and get a firm hold for the support of the plant which is above ground.
To make the soil open and porous, so that it can more readily absorb rain as it falls on the surface.
To check loss of water by evaporation.
To admit air to the roots of plants. Also to allow air to act chemically on the mineral and organic matter of the soil and make them available to the crop.
To raise the temperature of soils in the spring, or of damp soils at any time.
To mix manures and organic matter with the soil. The more thoroughly manure is distributed through the soil the more easily plants will get it and the greater will be its effect on the soil.
To destroy the insect enemies of the plant by turning them up to the frost and the birds.
To kill weeds. Weeds injure crops:
They waste valuable moisture by pumping it up from the soil and sending it out into the air through their leaves. In this way they do their greatest injury to crops.
They crowd and shade the crop.
They take plant food which the plant should have.
Spading and plowing bring about conditions necessary for the sprouting or germination of seeds.
Spading and plowing also tend to bring about conditions necessary for the very important work of certain of the soil bacteria.
PARTS OF A PLOW
It will be found that a good farm plow has the following parts (Fig. 50):
A standard or stock, the central part of the plow to which many of the other parts are attached.
A beam, to which the power is attached by which the plow is drawn. Some plows have wooden beams and others have iron beams.
Handles by which the plowman guides and steadies the plow and also turns it at the corners of the plowed ground in going about the field.
A clevis, which is attached to the end of the beam and is used to regulate the depth of plowing. To the clevis is attached a draft ring or shackle, to which the horse or team is fastened. To make the plow run deep the draft ring or shackle is placed in the upper holes or notches of the clevis; to make it run shallow the ring is placed in the lower holes. On some plows there are only notches in the clevis for holding the ring, they answer the same purpose as holes. The clevis is also used on some plows to regulate the width of the furrow. By moving the draft ring or shackle towards the plowed land the plow is made to cut a wider furrow, moving it away from the plowed land causes the plow to cut narrower.
Some plows have a double clevis so that the draft ring may be raised or lowered, or moved to right or left. With some plows the width of the furrow is adjusted by moving the beam at its attachment to the handles.
A share, called by some the point, which shears the bottom of the furrow slice from the land. The share should be sharp, especially for plowing in grass land and land full of tough roots. If the share, particularly the point, becomes worn so that it bevels from beneath upwards it will be hard to keep the plow in the soil, for it will tend to slide up to the surface. If this happens the share must be renewed or sharpened. Plows are being made now with share and point separate, and both of these reversible (Fig. 51), so that if either becomes worn on the under side it can be taken out and turned over and put back and it is all right, they thus become self-sharpening.
A mouldboard. This turns and breaks the furrow slice. The degree to which the mouldboard pulverizes depends on the steepness of its slant upward and the abruptness of its curve sidewise. The steeper it is and the more abrupt the curve, the greater is its pulverizing power. A steep, abrupt mouldboard is adapted to light soils and to the heavier soils when they are comparatively dry. This kind of a plow is apt to puddle a clay soil if it is quite moist. For breaking new land a plow with a long, gradually sloping share and mouldboard is used.
A landslide, which keeps the plow in place.
A coulter. Some plows have a straight knife-like coulter (Fig. 52) which is fastened to the beam just in front of the mouldboard and serves to cut the furrow slice from the land. In some plows this is replaced by an upward projection of the share; this is wide at the back and sharp in front and is called the shin of the plow from its resemblance to the shin bone. The coulter is sometimes made in the form of a sharp, revolving disk (Fig. 53), called a rolling coulter. This form is very useful in sod ground and in turning under vines and tall weeds. It also lessens the draft of the plow.
A jointer or skimmer which skims stubble and grass from the surface of the soil and throws them into the bottom of the furrow where they are completely covered. The jointer helps also to pulverize the soil.
A truck or wheel, attached under the end of the beam. This truck makes the plow run steadier. This is sometimes used to make the plow run shallower by setting it low down. This is not right, for it then acts as a brake and makes the plow draw harder. The depth of the furrow should be adjusted at the clevis.
A plow not only has parts but it has character also.
CHARACTERISTICS OF A GOOD PLOW
A good plow should be strong in build and light in weight.
The draft should be as light as possible.
The plow should run steadily.
A good plow should not only turn the soil but should pulverize it as well.
When plowing, the team should be hitched to the plow with as short traces as possible, and the plow should be so adjusted that it will cut furrows of the required width and thickness with the least possible draft on the team and the least exertion on the part of the plowman.
THE FURROW SLICE
In plowing, the furrow slice may be cut thin and wide and be turned over flat. This method is adapted to breaking new land and heavy sod land.
It may be cut thick and narrow and be turned up on edge.
Or it may be cut of such a width and depth that the plow will turn it at an angle of about forty-five degrees. By this last method the greatest amount of soil can be turned at least expense of labor; the furrow slice can be more thoroughly broken; the greatest surface is exposed to the action of the air, and plant food is more evenly distributed through the soil.
HOW DEEP SHALL WE PLOW?
We learned in a previous chapter that the roots of farm plants develop largely in that part of the soil which is worked by the plow; therefore, to have as much tilled soil as possible for root growth, we should generally plow as deep as possible without turning too much of the subsoil to the surface. Lands that have been plowed deep should be deepened gradually by plowing up a half-inch to an inch of subsoil each year until the plow reaches a depth of at least nine or ten inches.
There is an opinion among many farmers that sandy soils should not be plowed deep. But as these soils are apt to be leachy it seems best to fill them with organic matter to as great a depth as possible to increase their water-holding power, and this can best be done by plowing farm manures in deep.
In many parts of the South the farmers use very small plows and small animals to draw them. The result is that the soil is not prepared to a sufficient depth to allow of the large root development necessary for large crops. These farmers need larger tools and heavier animals if they expect to make much improvement in the yield of their crops. These small plows and this shallow plowing have done much to aid the washing and gulleying of the hill farms by rain. The shallow layer of loose soil takes in the rain readily, but as the harder soil beneath does not take the water as readily, the shallow plowed soil soon fills, then becomes mud, and the whole mass goes down the slope. The land would wash less if it had not been plowed at all, and least of all if it were plowed deep, for then there would be a deep reservoir of loose soil which would be able to hold a large amount of water until the harder lower soil could take care of it.
BREAKING OUT THE MIDDLES
Some farmers have a way when getting the land ready for a crop, of plowing the rows first and then "breaking out the middles" or spaces between after the crop is planted. This is a poor practice, as it interferes with thorough preparation of the soil. The ground can be more thoroughly plowed and broken up before the crop is planted than afterwards. This practice of leaving the middles interferes with proper harrowing and after-cultivation.
THROWING THE LAND UP IN RIDGES
Many farmers throw the land up into ridges with the plow and then plant on the ridge. When land is thrown into ridges a greater amount of surface is exposed to the air and a greater loss of moisture by evaporation takes place, therefore ridge culture is more wasteful of soil water than level culture. For this reason dry soils everywhere and most soils in dry climates should, wherever practicable, be left flat. On stiff, heavy soils which are slow to dry out, and on low bottom lands it may be desirable to ridge the land to get the soil dried out and warmed quicker in the spring. Late fall and early planter truck crops are often planted on the southern slopes of low ridges thrown up with the plow for warmth and protection from cold winds.
TIME TO PLOW
The time of plowing will depend somewhat on the nature of the soil, climate and the crop.
More plowing is done in the spring just before planting spring and summer crops than at any other time, excepting in localities that plant large areas of winter grain and truck. This spring plowing should be done early, for the spring plowing tends to dry the loosened soil somewhat and allows it to become warm at an earlier date, and at the same time the loosened soil tends to hold water in the lower soil for future use by the crop and allows the soil to take in spring rains more readily. If a cover crop or green manure crop is to be turned under in the spring it should be done early so as to prevent the crop to be turned under from pumping too much water out of the soil and thus interfering with the growth of the crop for which the land is being prepared.
There are some particular advantages to be gained by fall plowing in heavy soils:
Immediately after harvest the land is usually dry and easy to work.
The soil plowed at this time and left rough is acted upon physically by frost which pulverizes it, and chemically by rain and air which renders plant food available.
Insects are turned up and exposed to frost and birds.
A great number of weeds are destroyed and the land is more easily fitted for crops in the spring. Fall plowing should be done as early as possible, especially in the dryer regions, to catch all water possible. It is not advisable to plow sandy soils in the fall lest plant food be washed out of them.
When possible a cover crop should be put on fall plowed land where there is likely to be loss of plant food by leaching.
BARE FALLOW
The term "fallowing" is sometimes applied to the operation of plowing, and sometimes the land is left bare without a crop sometime after plowing; this is called "bare fallowing" the land.
Bare fallowing should not be practiced on all soils. It is adapted:
To dry climates and dry seasons where it is desirable to catch and save every possible drop of rainfall, and where plant food will not be washed out of the exposed soils by rains.
To heavy clay lands.
To lands that are foul with weeds and insects.
To sour soils which are sweetened by exposure to air and rain.
Light sandy soils should not be subjected to bare fallow unless they are very foul with weeds. They should always be covered with a crop to prevent loss of plant food by leaching.
CHAPTER XII
HARROWING AND ROLLING
HARROWING
After spading or plowing the next operation in the preparation of the soil is generally raking, harrowing or dragging. The objects of these operations are:
To break lumps and clods left by the plow and spade and to further pulverize the soil.
Harrowing and raking aid in controlling soil ventilation, and put the soil in better condition to absorb moisture.
They check the loss of moisture by making a mulch of fine loose earth on the surface.
The harrow and rake destroy the weeds.
The harrow brings about conditions favorable to the even distribution of seeds.
It is also the tool generally used to cover seeds sown broadcast.
Harrowing is generally done just before planting, and with some crops just after, to cover seeds or to smooth the ground. Harrowing is also done in the first stages of growth of some crops to kill weeds and make a soil mulch. The harrow should always follow the plow within a few hours unless it is desired to leave the land in a bare fall or winter fallow. At other times of the year the lumps of earth are apt to dry out and become hard and difficult to break. If there is but one work team on the farm it is a good plan during the plowing season to stop the plow in time to harrow the day's plowing before the day's work ends.
HARROWS
There are several types of harrows in use. They may be classified according to the style of their teeth or cutting parts; they are as follows:
Rolling cutter harrows.
Spring-toothed harrows.
Spike-toothed harrows.
Coulter-toothed harrows.
Chain harrows.
Brush harrows.
Plank or drag harrows.
These types vary in the depth to which they cut, and the degree to which they pulverize the soil.
Rolling cutter harrows. Harrows of this type (see Fig. 54) consist of one or more revolving shafts on which are arranged a number of concave disks. These disks are either entire, notched, or made of several pieces fastened together. Examples of these are the disk, cutaway and spading harrows. These harrows cut and move the soil deeper than the other types. They are especially adapted to work on heavy clay soils.
The value of this type of harrow as moisture preservers depends on the manner in which they are used. If the disks are so set that they cover but a portion of the surface with a mulch of fine earth they leave a ridge exposed to the action of the wind and sun and the rate of evaporation is greatly increased. The disks should be set at such an angle that the whole surface shall be stirred or covered. Soils which need the disk harrow should generally be gone over again with some shallower working tool to smooth the surface. An objection to the rolling cutters is that unless great care is taken they will leave the land in ridges and valleys.
The two gangs of disks throw the earth in opposite directions. They are generally set to throw it from the centre and the result is a shallow double furrow the width of the machine. By lapping each time the furrow is partially filled, but to get the land smooth a smoothing harrow should be used after the rolling cutter.
Spring-toothed harrows (Fig. 55). Spring-toothed harrows with their curved spring teeth enter the soil readily, draw moderately easy and pass over obstructions without much difficulty. They are very useful in new land that is full of roots and stumps and also stony land. They pulverize the soil to an average depth. They leave the soil in ridges. The ridges can be leveled by a smoother in the shape of a piece of plank attached to the rear of the harrow. On newly plowed grass land they tend to tear up the sod and leave it on the surface. They also tend to drag out coarse manures when plowed in.
The original and more common form of the spring-toothed harrow is a floating harrow when at work. That is, it rests on the points of the teeth and is dragged or floated over the ground. A newer form of spring-toothed harrow, sometimes called the fallow cultivator, is mounted on high wheels and its action is largely controlled by them. This form of harrow is claimed to do much better work than the floating harrow and may in a large measure displace the rolling cutter. The weight of this harrow is entirely taken from the soil except in the wheel tracks, and the entire action is that of pulverizing and lightening the soil.
Spike-toothed harrows (Fig. 56). The teeth of these harrows are round, square or diamond-shaped spikes fastened into a wood or iron frame. The teeth are set in a vertical position or are inclined to the rear. These harrows are shallow in their action; they run easily but tend to compact the soil more than the other types and are therefore better adapted to loose soils and to finishing off after the work of the deep cutting harrows. They are also used for covering seeds.
Coulter-toothed harrows. The coulter-toothed harrows (Fig. 57) have teeth resembling the coulter of a plow twisted or bent into various shapes. The Acme is a good example of this class of harrow. It cuts, turns and pulverizes the surface soil somewhat after the manner of the plow. It prepares a fine mulch and leaves an excellent seed bed. It is an excellent harrow to finish off with after using a rolling cutter.
Chain harrows. The chain harrow consists of a web of chains linked together. They have a wonderful power for breaking clods and are useful for collecting weeds. They shake the dirt from the weeds and roll them into heaps. Chain harrows tend to compact the soil.
Brush harrows. The brush harrow is a primitive form made by fastening brush to a long pole. Brush harrows are quite useful for brushing in seed and for pulverizing manure broadcasted on grass lands.
Plank harrows. The plank harrow (see Fig. 58) is made of several planks fastened together so that each plank overlaps the next one to it, like the clapboards of a house. This harrow is as good as a roller in fining and smoothing the surface soil. It is an excellent tool to use alternately with a spike or coulter-toothed harrow on lumpy soil. This tool rasps or grinds many of the lumps or clods which slip by the harrow teeth and presses others into the ground so that the harrow following can get a grip on them. It is a harrow that can be made on any farm. This planker is an excellent tool to smooth the surface, for broadcasting small seeds and for planting truck crops.
ROLLING
The objects of rolling are:
To compress the surface soil so that the harrow will do its work more efficiently, also to break clods or lumps that may have resisted the action of the harrow.
To smooth the surface of the soil for an even distribution of small seeds, and to firm the soil around such seeds after they are planted so that they will keep moist and sprout readily.
To give compactness to soils that are light and loose and thus enable them to hold moisture and plant food better.
To press into the ground the roots of plants partly dislodged by the frost.
To remove the conditions favorable to the development of many kinds of insects.
To sink surface stones so that they will not interfere with harvesting the crop.
Light porous soils may be rolled at any time, but clay soils can be rolled to advantage only when they are stiff and cloddy.
Spring-sown grain is often rolled as soon as sown. This is all right in ordinary spring weather, but if showers are frequent and the soil is quite moist the rolling should be omitted till after the grain is up. The same practice will apply to autumn-sown grain also. If the soil is dry the rolling helps it to pump water up to the seeds. But if it is moist and showers are frequent the combined action of the roller and the rain is to make so thick a crust that many of the seeds will not be able to force their way through it or will be smothered by poor ventilation. After the grain is up the rolling may be done to advantage, as it then makes a firm soil about the roots of the plants, a condition of benefit to grain crops.
The most simple form of roller is a solid or hollow cylinder of wood fastened into a frame by which it is drawn. Some rollers have spikes or blunt attachments fastened to their surfaces for breaking clods. A roller that is quite popular consists of a cylinder of pressed steel.
CHAPTER XIII
LEAVES
FACTS ABOUT LEAVES
We found in an earlier lesson that all of our farm plants have roots, stems, leaves, flowers, fruit and seeds. We studied the root first as being the most important part of the plant to the farmer. The seed was the next part studied, for that was considered the next most important, because the seed is the main reliance for new plants. The part next in importance is the leaf and that we will now study.
If you will go into the field and observe the leaves on a number of plants, you will find that the following facts are true:
They are all green.
They are flat and thin.
Many of them are very broad.
Some of the leaves on a single branch are larger than others on the same branch, and some have longer stems than others.
Most of them have a rather dark glossy upper surface and a lighter rougher under surface.
The leaves on the lower branches of the trees are spread out in a more or less flat layer and have their glossy surfaces all turned up, while those on branches in the tops of trees or shrubs are arranged all around the branch, the glossy surface being turned up.
What are the reasons for these facts?
A study of the work of the leaves and the conditions necessary for them to perform their work will help us to answer this question.
THE USES OF LEAVES TO PLANTS
Experiment.—(See Fig. 59). Take a pot or tumbler in which a young plant is growing, also a piece of pasteboard large enough to cover the top of the pot; cut a slit from the edge to the centre of the pasteboard, then place it on the top of the pot, letting the plant enter the slit. Now close the slit with wax or tallow, making it perfectly tight about the stem. If the plant is not too large, invert a tumbler over it, letting the edge of the tumbler rest on the pasteboard; if a tumbler is not large enough use a glass jar. If a potted plant is not convenient a slip or a seedling bean or pea placed in a tumbler of water will serve the purpose. Prepare several and place some in a sunny window and leave others in the room where it is darker, and observe them from time to time. In the case of those plants that were set in the sunny window moisture will be seen collecting on the inner surface of the tumbler. Where does this come from? It is absorbed from the soil by the roots and is sent with its load of dissolved plant food up through the stems to the leaves. There most of the water is passed from the leaves to the air and is condensed on the sides of the glass. A work of leaves then is to throw off or to transpire moisture and thus make room for a new supply of food-laden moisture. This water is thrown off through little pores or mouths or stomata which are very small and very numerous on the under side of the leaf. It will be noticed that the plant not placed in the sunlight transpires very little moisture, showing that sunlight helps the leaves in this work of transpiration.
How much water does a plant transpire or throw off from its leaves?
Experiment.—(See Fig. 60). Fill a common quart fruit jar or can with soil and plant in it a kernel of corn, a bean, a cotton seed or seed of some other plant. After the plant has grown to be twelve or fifteen inches high, cut a piece of pasteboard a little larger than the top of the jar, cut a hole in the centre as large as the stem of the plant and make a slit from edge to centre. Soak the pasteboard in melted wax or paraffine candle. Cool it and then place it over the jar, slipping it around the plant stem. Now solder the pasteboard to the jar with melted candle making the joints tight all the way around. Then close up the slit and the hole about the stem. The jar is now completely sealed and there is no way for water to escape except through the plant. The plant should be well watered before the jar is closed. Now weigh the jar and set in the sunlight. Weigh again the next day. The difference in the two weights will represent the amount of water transpired by the plant. The weighings may be repeated until moisture gives out. If it is desired to continue this experiment some time, a small hole should be cut in the pasteboard before it is fastened to the jar. This hole is for adding water to the jar from time to time. The hole should be kept closed with a cork. The amount of water added should always be weighed and account taken of it in the following weighings. While this plant is growing it will be well to wrap the jar with paper to protect the roots from the light.
It has been found that the amount of water necessary to grow a plant to maturity is equal to from 300 to 500 times the weight of the plant when dry.
This gives us an idea of the very great importance of water to plants.
Experiment.—Take a few leaves from a plant of cotton, bean, clover or other plant that has been growing in the sunlight; boil them for a few minutes to soften the tissues, then place them in alcohol for a day or until the green coloring matter is extracted by the alcohol. Wash the leaves by taking them from the alcohol and putting them in a tumbler of water. Then put them in saucers in a weak solution of iodine. The leaf will be seen to gradually darken; this will continue until it becomes dark purple or almost black (Fig. 61). We have already learned that iodine turns starch this color, so we conclude that leaves must contain starch. (Five or ten cents worth of tincture of iodine from a drug store diluted to about the color of weak tea will be sufficient for these leaf experiments.)
Experiment.—If a potted plant was used for the last experiment, set it away in a dark closet after taking the leaves for the experiment. A day or two after, take leaves from it before removing it from the closet. Boil these leaves and treat them with alcohol as in the previous experiment. Then wash them and test them with iodine as before. No starch will be found in the leaves (Fig. 62). The starch that was in them when placed in the closet has disappeared. Now paste some thick paper labels on some of the leaves of a plant exposed to the sunlight. After a few hours remove the leaves that have the labels on them, boil, treat with alcohol and test with the iodine. In this case starch will be found in all parts of the leaf except the part over which the label was pasted (Fig. 63). If the sunlight is intense and the label thin, some starch will appear under it.
According to these last experiments, leaves contain starch at certain times, and this starch seems to appear when the leaf is in the sunlight and to disappear when the light is cut off. The fact is that the leaves manufacture starch for the plant and sunlight is necessary for this work. The starch is then changed to sugar which is carried by the sap to other parts of the plant where it is again changed to starch to be built into the plant structure or stored for future use.
Experiment.—Take leaves from a plant of silver-leaf geranium growing in the sunlight. If this plant cannot be had, the leaves from some other variegated white and green leaved plant will do. Boil these leaves, treat with alcohol, wash and test with iodine (Fig. 64). Starch will be found in the leaf wherever there was green coloring matter in it, while the parts that were white will show no starch. The green coloring matter seems to have something to do with the starch making, in fact starch is manufactured only where it is present. This coloring matter is called chlorophyl or leaf green.
We are told by the chemists that this starch is made from carbon and water. There exists in the air a gas called carbonic acid gas; this gas is composed of carbon and oxygen. It is breathed out of the lungs of animals and is produced by the burning and decay of organic matter. The under side of the leaf contains hundreds of little pores or mouths called stomata. This gas mixed with air enters these mouths. The green part of the leaf aided by the sun takes hold of the gas and separates the carbon from the oxygen. The oxygen is allowed to go free, but the carbon is made to unite with water and form starch.
Experiment.—The escape of this oxygen gas may be seen by taking some water weed from either fresh or salt water and placing it in a glass jar of the kind of water from which it came, then set the jar in the sunlight. After a time bubbles of gas will be seen collecting and rising to the surface. If a mass of weed like the green scum of fresh water ponds or green sea lettuce be used, the bubbles of gas will become entangled in the mass and will cause it to rise to the surface of the water. At the same time prepare another jar of the weed and place it somewhere out of the sun; very few bubbles will be seen to rise and the weed will settle to the bottom of the jar (Fig. 65).
All of the food of the plant, whether taken from the air or from the soil is digested in the leaves, and sunlight and air are necessary for this work.
Another function of leaves then is to digest food for the plant.
Important functions of leaves then are:
To transpire moisture sent up by the roots.
To manufacture starch by combining some of the water sent up by the roots with carbon taken from the air.
To digest the starch and food sent up by the roots.
To do these things well leaves must be connected with a strong, healthy root system and must have plenty of light and air.
We are now ready to give reasons for the facts about leaves mentioned in the first part of the chapter (see page 109).
Leaves are green because the green coloring matter is necessary for the leaf to do its work.
Leaves are flat and thin and broad in order that they may present a large surface to the air and sunlight.
Some leaves on the branch are larger than others because in the struggle for light and air they have had a better chance than the others or they have had more of the food which has come up from the root.
Some of the leaves have developed longer stems than others in their effort to reach out after light and air.
Most leaves have the little mouths through which air is taken in and water and oxygen given out on the rough side, and that side is turned down toward the earth probably so that rain and dust will not choke the little pores.
The leaves of the lower branches tend to spread out in a broad, flat plane because in the effort to get light no leaf will grow directly under and in the shadow of another, while on those branches which grow straight up from the top of the tree the leaves can get light from all sides and so arrange themselves around the stem.
Is it of any value to the plant grower to know these facts about leaves? It is, for knowing these things he can better understand the necessity of caring for the leaves of his growing plants to see that their work is not interfered with.
HOW THE WORK OF SOME LEAVES IS INTERFERED WITH
Many people who grow house plants have trouble in keeping them well clothed with leaves, for instance, the geranium and the rubber plant. The leaves are constantly turning yellow and dropping off or drying up. This sometimes occurs from over-watering or not sufficiently watering the soil in the pot or box. If the watering is all right the trouble may occur in this way: The air of the house is quite dry, especially in winter. As a result transpiration from the leaf may be excessive. More water is transpired than is necessary, consequently more is pumped by the roots and with it more food is sent to the leaf than it can take care of. As the excess of water is transpired the excess of food is left in the leaf. The tendency is to clog its pores and therefore interfere with its work, and gradually weaken and finally kill it. The remedy for this is to spray the leaves frequently so as to keep the air about them moist and so check transpiration. Keeping a vessel of water near them helps also as this tends to keep the air moist. Dust sometimes chokes the leaves. Washing or spraying remedies this.
Sometimes house plants, and out-door plants as well, become covered with a small, green insect called the plant louse or aphis. This insect has a sharp beak like a mosquito and it sucks the juices from the leaf and causes it to curl up, interfering with its work and finally killing it. Frequent spraying with water will tend to keep these away. A surer remedy against them is to spray the plants with weak tobacco water made by soaking tobacco or snuff in water, or to fumigate them with tobacco smoke. Sometimes the under side of the leaf becomes infested with a very small mite called red spider because it spins a web. These mites injure the leaf by sucking sap from it. They can be kept in check by frequent spraying for they do not like water. If, then, we are careful to frequently spray the leaves of our house plants we will have very little trouble from aphis, red spider or over transpiration. The aphis, or plant louse, is often very numerous on out-door plants, for instance, the rose, chrysanthemum, cabbage, and fruit trees. They vary in color from green to dark brown or black. They are treated in the same way as those on the house plants. Some familiar out-door insects which interfere with leaf work are the common potato bug, the green cabbage worm, the rose slug, the elm tree leaf beetle, the canker worm, the tomato worm. These insects and many others eat the leaves (Fig. 67). They chew and swallow their food and are called chewing insects. All insects which chew the leaves of plants can be destroyed by putting poison on their food. The common poisons used for this purpose are Paris green and London purple, which contain arsenic, and are used at the rate of one teaspoonful to a pail of water or one-fourth pound to a barrel of water. This is sprinkled or sprayed on the leaves of the plants. Another poison used is white hellebore. This loses its poisoning qualities when exposed to the air for a time. Therefore it is safer to use about the flower garden and on plants which are soon to be used as food or whose fruit is to be used soon, like cabbages and current bushes. This hellebore is sifted on the plant full strength, or it may be diluted by mixing one part of hellebore with one or two parts of flour, plaster, or lime. It is also used in water, putting one ounce of hellebore in three gallons of water and then spraying it on the plants. Plants may be sprayed by using a watering pot with a fine rose or sprinkler, or an old hair-brush or clothes-brush. For large plants or large numbers of smaller plants spray pumps of various sizes are used. Sometimes chewing insects on food plants and sucking insects on all plants are treated by spraying them with soapy solutions or oily solutions which injure their bodies.
The work of the leaf is also interfered with by diseases which attack the leaves and cause parts or the whole leaf to turn yellow or brown or become blistered or filled with holes. The common remedy for most of these diseases is called the "Bordeaux Mixture." It is prepared as follows: Dissolve four pounds of blue vitriol (blue stone, or copper sulphate) in several gallons of water. Then slake four pounds of lime. Mix the two and add enough water to make a barrelful. The mixture is then sprayed on the plants.
For more detailed directions for spraying plants and combating insects and diseases write to your State Experiment Station and to the United States Department of Agriculture at Washington, D.C.
The work of the leaves of house plants is often interfered with by not giving them sufficient sunlight. Garden and field plants are sometimes planted so thick that they crowd each other and shut the light and air from each other, or weeds are allowed to grow and do the same thing, the result being that the leaves cannot do good work and the plant becomes weak and sickly. Weeds are destroyed by pulling them up and exposing their roots to the sun. This should be done before the weeds blossom, to prevent them from producing fresh seeds for a new crop of weeds. Some weeds have fleshy roots—for example, dock, thistle—in which food is stored; these roots go deep in the ground, and when the upper part of the plant is cut or broken off the root sends up new shoots to take the place of the old. Some have underground stems in which food is stored for the same purpose. The surest way to get rid of such weeds, in fact, of all weeds, is to prevent their leaves from growing and making starch and digesting food for them. This is accomplished by constantly cutting off the young shoots as soon as they appear above the soil, or by growing some crop that will smother them. The constant effort to make new growth will soon exhaust the supply of stored food and the weed will die.
CHAPTER XIV
STEMS
WHAT ARE STEMS FOR?
Visit the farm or garden and the fields to examine stems and study their general appearances and habits of growth. Notice that many plants, like the trees, bushes and many vegetable and flowering plants, have stems which are very much branched, while others have apparently single stems with but few or no branches. Examine these stems carefully and note that there are leaves on some part of all of them and that just above the point where each leaf is fastened to the stem there is a bud which may sometime produce a new branch (Fig. 68). If the stems of trees and other woody plants be examined in the winter after the leaves have fallen, it will be seen that the buds are still there, and that just below each bud is a mark or leaf scar left by the fallen leaf. These buds are the beginnings of new branches for another year's growth. On some branches will be found also flowers and fruit or seed vessels.
Buds and leaves or buds and leaf scars distinguish stems from roots. Some plants have stems under the soil as well as above it. These underground stems resemble roots but can be distinguished from them by the rings or joints where will be found buds and small scale-like leaves (Fig. 69). Quitch-grass or wiregrass, Burmuda grass, white potato and artichoke are examples of underground stems.
Now study the habit of growth of these stems. Notice that:
Some plants grow erect with strong, stiff stems, for example, corn, sunflower, maple, pine, elm and other trees. Many of these erect stems have branches reaching out into the air in all directions. Stand under a tree close to the stem or trunk and look up into the tree and notice that the leaves are near the outer ends of the branches while in the centre of the tree the branches are nearly bare. Why is this? If you remember the work of leaves and the conditions necessary for their work you will be able to answer this question. Leaves need light and air for their work, and these erect, branching stems hold the leaves up and spread them out in the light and air.
Notice that where several trees grow close together, they are one-sided, and that the longest and largest branches are on the outside of the group and that they have more leaves than the inner branches. Why? Why do the trees in thick woods have most of the living branches and bear most of their leaves away up in the top of the tree?
Some stems instead of standing up erect climb up on other plants or objects by means of springlike tendrils which twist about the object and so hold up the slender stem. On the grape vine these tendrils are slender branches. On the sweet pea and garden pea they are parts of the leaves. The trumpet creeper and English ivy climb by means of air roots. The nasturtium climbs by means of its leaf stems.
Other stems get up into the light and air with their leaves by twining about upright objects. For example, the morning glory and pole bean.
Some stems will be found that spread their leaves out to the sun by creeping over the ground. Sweet potato, melon, squash, and cucumber vines are examples of such plants.
One use of the stems of plants then is to support the leaves, flowers and fruit, and expose them to the much needed light and air.
Experiment.—Get a piece of grape vine and cut it into pieces four or five inches long; notice that the cut surface appears to be full of little holes. Cut a piece from between joints, place one end in your mouth and blow hard. It will be found that air can be blown through the piece of vine. Now pour about an inch of water in a tumbler or cup and color it with a few drops of red ink. Then stand some of the pieces of grape vine in the colored water. In a few hours the colored water will appear at the upper ends of the sticks. Capillary force has caused the colored water to rise through the small tubes in the vine. Repeat this experiment with twigs of several kinds of trees and soft green plants, as elm, maple, sunflower, corn, etc. It will not be possible to blow through these twigs, but the red water will rise through them by osmose, and in a few hours will appear at the upper ends. If some leaves are left on the stems the colored water will appear in them. Some white flowers can be colored in this way.
In this manner the stem carries plant food dissolved in water from the roots to the leaves, and after the leaves have digested it carries it back to various parts of the plant.
The stem then serves as a conductor or a passage for food and moisture between roots and leaves.
Visit a strawberry bed or search for wild strawberry plants. Notice that from the older and larger plants are sent out long, slender, leafless stems with a bud at the tip. These stems are called runners. Find some runners that have formed roots at the tip and have developed a tuft of leaves there, forming new plants. Find some black raspberry plants and notice that some of the canes have bent over and taken root at the tips sending up a new shoot and thus forming a new plant. You know how rapidly wire grass and Bermuda grass will overrun the garden or farm. One way in which they do this is by sending out underground stems which take root at the joints and so form new plants.
Another use of the stem then is to produce new plants.
On the farm we make use of this habit of stems when we wish to produce new white potato plants. We cut an old potato in pieces and plant them. The buds in the eyes grow and form new plants. One way of getting new grape plants is to take a ripened vine in the fall and cut it in pieces with two or three buds and plant them so that one or both of the buds are covered with soil. The pieces will take root and in the spring will send up new shoots and thus form new plants.
You can obtain new plants from geranium, verbena, nasturtium and many other flowering plants, by cutting and planting slips or parts of the stems from them.
In parts of the South new sweet potato plants are obtained by cutting parts of the stems from growing plants and planting them.
Florists produce large numbers of new plants by taking advantage of this function of stems.
Experiment.—Take a white potato which is a thickened stem and place it in a warm, dark place. It will soon begin to sprout or send out new stems, and as these new stems grow the potato shrinks and shrivels up. Why is this? It is because the starch and other material stored in the potato are being used to feed the new branches. When we plant potatoes in the garden and field the new plants produced from the eyes of the potato are fed by the stored material until they strike root and are able to take care of themselves.
All stems store food for the future use of the plant.
Annual plants, or those which live but one year, store food in their stems and leaves during the early part of their growth. During the fruiting or seed forming season this food material is transferred to the seeds and there stored, and the stems become woody. This is a fact to bear in mind in connection with the harvesting of hay or other fodder crops. If we let the grass stand until the seeds form in the head, the stem and leaves send their nourishment to the seeds and become woody and of less value than if cut before the seeds are fully formed.
In plants of more than one year's growth the stored food is used to give the plant a start the following season, or for seed production.
The rapid growth of leaf and twig on trees and shrubs in spring is made from the food stored in the stem the season before.
Sago is a form of starch stored in the stem of the sago palm for the future use of the plant.
Maple sugar is made from the food material stored in the trunk of the maple tree for the rapid growth of twig and leaf in the spring.
Cane sugar is the food stored in the sugar cane to produce new plants the next season.
If we examine the stem of a tree that has been cut down we find that it is woody, that the wood is arranged in rings or layers and that the outer part of the stem is covered with bark. We will notice also that the wood near the centre of the tree is darker than the outer part. This inner part is called the heart wood of the tree. The lighter wood is called the sap wood. It is through the outer or sap wood that the water taken in by the root is passed up to the leaves where the food which it carries is digested and then sent back to the plant. The returning digested food is sent back largely through the bark. Between the bark and the wood is a very thin layer which is called cambium. This is the active growing tissue of the stem. In the spring it is very soft and slippery and causes the bark to peel off easily. This cambium builds a new ring of wood outside of the old wood and a new ring of bark on the inside of the bark. In this way the tree grows in diameter.
Now if the bark is injured, or any part of the stem, all parts below the wound are cut off from the return supply of digested food and their growth is checked. When such a wound does occur, or if a wound is made by cutting off a branch, the cambium sets to work to repair the damage by pushing out a new growth which tends to cover the wound. We can help this by covering the wound and keeping the air from it to prevent its drying and to keep disease from attacking it before it is healed.
HOW THE WORK OF THE STEM MAY BE INTERFERED WITH
If there are any peach trees near by, examine the trunks close to the ground, even pulling away the soil for a few inches. You will very likely find a mass of gummy substance oozing from the tree. Pull this away and in it and in the wood under it will be found one or more yellowish white worms. These are tree borers. They will be found in almost all peach trees. They interfere with the work of the stem and in many cases kill the trees. These worms may be kept somewhat in check by keeping papers wrapped about the lower part of the tree. But the surest way to keep them in check is to dig them out, spring and fall, with a knife and wire.
Borers attack the other fruit trees and also ornamental trees and shrubs.
Rabbits sometimes gnaw the bark from trees during severe winters.
Careless workmen sometimes injure the bark of trees by allowing plows and mowing machines or other tools which they are using among them to come in contact with the trees and injure the bark.
Young trees purchased from the nursery generally have a label fastened to them with a piece of wire. Unless this wire is removed or is carefully watched and enlarged from time to time it will cut into the bark as the stem grows and interfere with its work and often kill the top of the tree or injure a main branch.
These are a few ways in which the work of the stem is sometimes checked and the plant injured thereby.
CHAPTER XV
FLOWERS
In our study of the parts of plants the flower and fruit have been given the last place because in the growing of most farm plants a knowledge of the functions of the flower is of less importance than that of the roots, leaves and stems. However, a knowledge of these parts is necessary for successful fruit culture and some other horticultural industries.
As with the other parts of the plant our study will not be exhaustive but will be simply an attempt to bring out one or two important truths of value to most farmers.
In the study of flowers the specimens used for study will depend upon the time of the year in which the studies are made and need not necessarily be the ones used here for illustration.
FUNCTION OR USE OF FLOWERS TO PLANTS
Of what use is the flower to the plant?
You have doubtless noticed that most flowers are followed by fruit or seed vessels. In fact, the fruit and seeds are really produced from the flower, and the work of most flowers is to produce seeds in order to provide for new plants.
To understand how this comes about it will be necessary to study the parts of the flower and find out their individual uses or functions.
PARTS OF A FLOWER
If we take for our study any of the following flowers: cherry, apple, buttercup, wild mustard, and start from the outside, we will find an outer and under part which in most flowers is green. This is called the calyx (Figs. 70-74). In the buttercup and mustard the calyx is divided into separate parts called sepals. In the cherry, peach and apple, the calyx is a cup or tube with the upper edge divided into lobes.
Above the calyx is a broad spreading corolla which is white or brightly colored and is divided into several distinct parts called petals. The petals of one kind of flower are generally different in shape, size and color from those of other flowers. In some flowers the petals are united into a corolla of one piece which may be funnel-shaped, as in the morning glory or petunia of the garden, or tubular as in the honeysuckle, wheel-shaped as in the tomato and potato, or of various other forms.
Within the corolla are found several bodies having long, slender stems with yellow knobs on their tips. These are called stamens. The slender stems are called stalks or filaments and the knobs anthers. The anthers of some of the stamens will very likely be found covered with a fine, yellow powder called pollen. This pollen is produced within the anther which, when ripe, bursts and discharges the pollen.
The stamens vary greatly in number in different kinds of flowers. In the centre of the cherry, peach, or mustard flower will be found an upright slender body called the pistil. In the peach and cherry the pistil has three parts, a lower rounded, somewhat swollen part called the ovary, a slender stem arising from it called the style, and a slight enlargement at the top of the style called the stigma. The stigma is generally roughened or sticky. If the ovary is split open, within it will be found a little body called an ovule, which is to develop into a seed.
In the apple flower the pistils will be found to have one ovary with five styles and stigmas and in the ovary will be several ovules.
In the buttercup will be found a large number of small pistils, each consisting of an ovary and stigma.
The parts of different flowers will be found to vary in color, in shape, in relative size and in number. In some flowers one or more of the parts will be found wanting.
Examine a number of flowers and find the parts.
FUNCTIONS OF THE PARTS OF THE FLOWERS
Now what are the uses of these parts of the flower?
If we watch a flower of the peach or cherry from week to week, we will see that the pistil develops into a peach or cherry which bears within a seed from which a new plant will be produced if the seed is placed under conditions necessary for germination or sprouting.
The pistils of the flowers of other plants will be found to develop into fleshy fruits, hard nuts, dry pods or husks containing one or more seeds.
The work of the pistil or pistils of flowers then is to furnish seeds for the production of new plants.
The botanists tell us that a pistil will not produce seeds unless it is fertilized by pollen from the same kind of flower falling on its stigma.
The work of the stamen then is to produce pollen to fertilize the pistils. Pistils and stamens are both necessary for the production of fruit and seed. They are therefore called the essential or necessary parts of the flower.
The botanists also tell us that nature has provided that in most cases the pistils shall be fertilized by the pollen of some other flower than their own, as this produces stronger seeds.
How is the pollen carried from flower to flower?
Go into the garden or field and watch the bees and butterflies flying about the flowers, resting on them and crawling into them. They are seeking for nectar which the flower secretes. As they visit plant after plant, feeding from many flowers, their bodies become more or less covered with pollen as they brush over the stamens. Some of this pollen in turn gets rubbed off on the stigmas of the pistils and they become fertilized. Thus the bees and some other insects have become necessary as pollen carriers for some of the flowers and the flowers in turn feed them with sweet nectar.
This gives us a hint as to one use of the corollas which spreads out such broad, brightly-colored, conspicuous petals. It must be that they are advertisements or sign boards to attract the bees and to tell them where they can find nectar and so lead them unconsciously to carry pollen from flower to flower to fertilize the pistils. The act of carrying pollen to the pistil is called pollination, and carrying pollen from the stamens of one flower to the pistil of another flower is called cross pollination.
If we examine a blossom bud just before it opens we will see only the calyx. Everything else will be wrapped up inside of it. Evidently, then, the calyx is a protecting covering for the other parts of the flower until blossoming time.
The corolla will be found carefully folded within the calyx and also helps protect the stamens and pistil.
Some flowers do not produce bright-colored corollas to attract the bees, for examples, the flowers of the grasses, wheat, corn, and other grains, the willows, butternuts, elms, pines and others. But they produce large amounts of pollen which is carried by the wind to the pistils.
You have sometimes noticed in the spring that after a rain the pools of water are surrounded by a ring of yellow powder and you have perhaps thought it was sulphur. It was not sulphur but was composed of millions of pollen grains from flowers. One spring Sunday I laid my hat on the seat in church. When I picked it up at the end of the service I found considerable dust on it. I brushed the dust off, but on reaching home I found some remaining and noticed that is was yellow, so I examined it with a magnifying glass and found that it was nearly all pollen grains. Then I rubbed my finger across a shelf in my room and found it slightly dusty; the magnifying glass showed me that this dust was half pollen. This shows what a great amount of pollen is produced and discharged into the air, and it shows that very few pistils could escape even if they were under cover of a building.
To make sure of cross pollination nature has in some cases placed the stamens and pistils in different flowers on the same plant. This will be found true of the flowers of the squashes, melons and cucumber. Below some of the flower buds will be seen a little squash, melon or cucumber (Fig. 75). These are the ovaries of pistils and the stigmas will be found within the bud or will be seen when the bud opens. But no stamen will be found here. Other flowers on these plants will be found to possess only stamens. These staminate flowers produce pollen and then die. They do not produce any fruit, but their pollen is necessary for the little cucumbers, squashes and melons to develop.
Another example is the corn plant. Here the pistils are on the ear, the corn silk being the styles and stigmas, while the pollen is produced in the tassel at the top of the plant.
With some plants we find that not only are the pistils and stamens in separate flowers but the staminate and pistilate flowers are placed on different plants. This will be found true of the osage orange and the willow.
In many flowers that have both stamens and pistils or are perfect flowers the stigmas and pollen ripen at different times.
With some varieties of fruit it is found that the pistils cannot be fertilized by pollen of the same variety. This is true of most of our native plums. For example, the pistils of the wild goose plum cannot be fertilized by pollen of wild goose plums even if it comes from other trees than the one bearing the pistils. They must have pollen from another variety of plum.
VALUE OF A KNOWLEDGE OF THE FLOWER
Many times it happens that a farmer or a gardener wants to start a strawberry bed and buys plants of a variety of berries that have the reputation of being very productive. He plants them and cultivates them carefully, and at the proper time they blossom very freely, and there is promise of a large crop, yet very few berries appear and this continues to be the case. Not satisfied with them he buys another variety and plants near them, and after that the old bed becomes very productive. Now why is this? It happens that the flowers of some varieties of strawberries have a great many pistils but no stamens, or very few stamens, and there is not pollen enough to fertilize all of the blossoms, and when such a variety is planted it is necessary to plant near it some variety that produces many stamens and therefore pollen enough to fertilize both varieties in order to be sure of a crop. Those strawberries which produce flowers with only pistils are called pistilate varieties, while those with both stamens and pistils are called perfect varieties (Fig. 78). In planting them there should be at least one row of a perfect variety to every four or five pistilate rows. |
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