The First Book of Farming Part 16

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.

[Ill.u.s.tration: FIG. 68.

A horse-chestnut stem showing leaves, buds, and scars where last year's leaves dropped off.]

[Ill.u.s.tration: FIG. 69.--AN UNDERGROUND STEM Buds show distinctly at points indicated by _b_.]

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, b.u.t.tercup, 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 b.u.t.tercup 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 k.n.o.bs on their tips. These are called stamens. The slender stems are called stalks or filaments and the k.n.o.bs 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 b.u.t.tercup 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?

[Ill.u.s.tration: FIG. 70.--FLOWER OF CHERRY.

_a_, pistil; _b_, stamen; _c_, corolla; _d_, calyx; _e_, section of flower showing ovary with ovule. (Drawing by M.E. Feltham.)]

[Ill.u.s.tration: FIG. 71.

1. Flower of apple; _b_, stamens; _c_, corolla; _d_, calyx. 2. Section of same; _a_, style; _e_, compound ovary; _f_, filament; _g_, anther.

(Drawing by M.E. Feltham.)]

[Ill.u.s.tration: FIG. 72.

_A._ Pistil of flowering raspberry; _e_, ovary; _t_, style; _s_, stigma. _B._ Stamen of flowering raspberry; _f_, filament; _g_, anther; _p_, pollen.]

[Ill.u.s.tration: FIG. 73.--FLOWER OF b.u.t.tERCUP.

_c_, petals; _d_, sepals; _h_, ripened pistils, or fruit. (Drawing by M.E. Feltham.)]

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 b.u.t.terflies 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 advertis.e.m.e.nts 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 gra.s.ses, wheat, corn, and other grains, the willows, b.u.t.ternuts, 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 gla.s.s 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 gla.s.s 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 cuc.u.mber.

Below some of the flower buds will be seen a little squash, melon or cuc.u.mber (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 cuc.u.mbers, 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 ta.s.sel 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.

[Ill.u.s.tration: FIG. 74.

A magnolia flower showing central column of pistils and stamens, the pistils being above and the stamens below them.]

[Ill.u.s.tration: FIG. 75.--FLOWERS OF SQUASH.

_A_, pistillate flower; _B_, staminate flower. A means of insuring cross-pollination.]

We have learned that certain varieties of plums cannot be fertilized by pollen from the same variety, and to make them fruitful some other variety must be planted among them to produce pollen that will make them fruitful. This is more or less true of all our fruits. Therefore it is not best generally to plant one variety of fruit by itself. Not knowing this some orchardists have planted large blocks of a single variety of fruit which has been unfruitful till some other varieties have been planted near them or among them.

A knowledge of the necessity of pollination is very important to those gardeners who grow cuc.u.mbers, tomatoes, melons and other fruiting plants in greenhouses. Here in most cases the pollination is done by hand.