The Flower And The Seed

Categories: THE PLANT

Some people think that the flowers by the wayside are for the purpose of

beautifying the world and increasing man's enjoyment. Do you think this

is true? Undoubtedly a flower is beautiful, and to be beautiful is one

of the uses of many flowers; but it is not the chief use of a flower.



You know that when peach or apple blossoms are nipped by the spring

frost the fruit crop is in danger. The fruit of the plant bears the br />
seed, and the flower produces the fruit. That is its chief duty.






Do you know any plant that produces seed without flowers? Some one

answers, "The corn, the elm, and the maple all produce seed, but have no

flower." No, that is not correct. If you look closely you will find in

the spring very small flowers on the elm and on the maple, while the ear

and the tassel are really the blossoms of the corn plant. Every plant

that produces seed has flowers, although they may sometimes seem very

curious flowers.






Let us see what a flower really is. Take, for example, a buttercup,

cotton, tobacco, or plum blossom (see Figs. 31 and 32). You will find on

the outside a row of green leaves inclosing the flower when it is still

a bud. These leaves are the _sepals_. Next on the inside is a row of

colored leaves, or _petals_. Arranged inside of the petals are some

threadlike parts, each with a knob on the end. These are the _stamens_.

Examine one stamen closely (Fig. 33). On the knob at its tip you should

find, if the flower is fully open, some fine grains, or powder. In the

lily this powder is so abundant that in smelling the flower you often

brush a quantity of it off on your nose. This substance is called

_pollen_, and the knob on the end of the stamen, on which the pollen is

borne, is the _anther_.






The pollen is of very great importance to the flower. Without it there

could be no seeds. The stamens as pollen-bearers, then, are very

important. But there is another part to each flower that is of equal

value. This part you will find in the center of the flower, inside the

circle of stamens. It is called the _pistil_ (Fig. 32). The swollen tip

of the pistil is the _stigma_. The swollen base of the pistil forms the

_ovary_. If you carefully cut open this ovary you will find in it

very small immature seeds.




_a_, anther; _f_, filament]



Some plants bear all these parts in the same flower; that is, each

blossom has stamens, pistil, petals, and sepals. The pear blossom and

the tomato blossom represent such flowers. Other plants bear their

stamens and pistils in separate blossoms. Stamens and pistils may even

occur in separate plants, and some blossoms have no sepals or petals at

all. Look at the corn plant. Here the tassel is a cluster of many

flowers, each of which bears only stamens. The ear is likewise a cluster

of many flowers, each of which bears only a pistil. The dust that you

see falling from the tassel is the pollen, and the long silky threads of

the ear are the stigmas.






Now no plant can bear seeds unless the pollen of the stamen falls on the

stigma. Corn cannot therefore form seed unless the dust of the tassel

falls upon the silk. Did you ever notice how poorly the cob is filled on

a single cornstalk standing alone in a field? Do you see why? It is

because when a plant stands alone the wind blows the pollen away from

the tassel, and little or none is received on the stigmas below.






In the corn plant the stamens and pistils are separate; that is, they do

not occur on the same flower, although they are on the same plant. This

is also true of the cucumber (see Fig. 35). In many plants, however,

such as the hemp, hop, sassafras, willow, and others, the staminate

parts are on one plant and the pistillate parts are on another. This is

also true in several other cultivated plants. For example, in some

strawberries the stamens are absent or useless; that is, they bear no

good pollen. In such cases the grower must see to it that near by are

strawberry plants that bear stamens, in order that those plants which do

not bear pollen may become _pollinated_; that is, may have pollen

carried to them. After the stigma has been supplied with pollen, a

single pollen grain sends a threadlike sprout down through the stigma

into the ovary. This process, if successfully completed, is called

_fertilization_.





=EXERCISE=



Examine several flowers and identify the parts named in the last

section. Try in the proper season to find the pollen on the maple,

willow, alder, and pine, and on wheat, cotton, and the

morning-glory.



How fast does the ovary of the apple blossom enlarge? Measure one

and watch it closely from day to day. Can you find any plants that

have their stamens and ovaries on separate individuals?