How Plants Reproduce (1957)

the story of how plants reproduce is one of the most wonderful stories in nature it is a story which we cannot fully explain it is the story of life itself life endlessly repeated season after season during the springtime the warm days of summer plant after plant displays its blossoms and goes on to produce fruits and seeds most of the plants we are familiar with have several main parts there are the roots which anchor the plant in the soil and absorb the moisture and minerals necessary for its growth another main part of the plant is the stem which supports the leaves flowers and later the fruit the leaf of the plant is the part that manufactures food using chlorophyll and sunlight to combine carbon dioxide and water into food materials the flower is the part of the plant that we usually think of in terms of its beauty but like the roots the leaves and the stem it has an important part to play the flower is the part that makes it possible for many plants to reproduce if the flower is successful a plant will provide for new plants the beauty and fragrance of flowers are important but not just because we enjoy them color and fragrance help the flower and therefore help the plant it grows on let's examine some familiar garden flowers to see what the parts of a flower are and what each of them does before most flowers open they are protected by green leaf like parts called sepals the sepals unfold when a flower is ready to bloom at the base of this flower you can see sepals which have opened to form a circle around the blossom inside the sepals is a second circle of parts called petals the petals or the showy part of the flower usually colored within the pedals is another circle of parts called stamens sometimes harder to see than the petals but very important to the flower if you touch the stamens you will find them covered with a yellow powdery dust called pollen greatly enlarged a stamen looks like this it has a tiny stalk called a filament topped off with an oblong end the anther the anther holds the pollen grains in the very center of the blossom is the fourth important part of the flower the pistol a pistol looks something like a tiny vase with the larger part at the bottom containing the ovals a slender neck and a sticky top called the stigma now that we know the names of the four parts of a flower let's look at their locations once again there are sepals the colorful petals stamens and the pistol have you ever walked in an orchard when the apple trees were in bloom if you have you know that the trees with their masses of delicate flowers are an attractive site attractive to bees as well as ourselves hundreds of them buzz about gathering nectar their bodies dusty with pollen bees are attracted to flowers by the fragrance as bees gather nectar they help the flower in a very important way or before a flower can form a seed pollen must be transferred from the stamen to the pistil sometimes the pollen is carried by a bee or other insect sometimes it is carried by the wind and sometimes it simply Falls greatly and large this is how pollen looks as you can see pollen grains from different flowers have different shapes bees usually go from one flower to another of the same kind so a pollen that rubs off the bee is the right kind of pollen for that flower when pollen is carried to the pistil either by the wind or by a bee each grain begins to grow sending down a tiny tube or the ovules within the bulb like base of the pistil the first pollen tube to meet the ovule joins with it in a process called fertilization to form a new cell the success of the flower depends upon that moment of fertilization without it the flower fades useless to the plant of course after fertilization the petals are no longer needed and they drop off but part of a fertilized flower remains inside the part that remains is the single cell that was formed by fertilization it begins to grow it divides into two cells these cells grow and divide and grow and divide over and over until there are many cells which take shape into a seed a seed within a fruit for every fruit there was once a blossom that was fertilized and so every fruit is the result of a flower that completed its function much as we like many fruits the plant did not produce the fruit simply for us to enjoy the seeds are the important part of the fruit to the plant or from the seeds new plants like the old one will grow life will be passed along to another generation when we carry a fruit away to eat it and throw away the seeds maybe that they will fall in a better place to grow than they would have had under the tree in this way the fruit may help the seeds a complete flower is one that has all of the four parts sepals petals stamens and pistils but not all flowers are alike some do not have all four parts and others have parts that look different from the way we expect them to look it is not easy to find the sepals of a tulip for instance because tulips sepals and petals look exactly alike the only way to tell sepals from petals is to see which are outside the three which are outside are the sepals here is the pistol in the center of the tulip the next circle of parts should be stamens covered with yellow polymer they are stamens but here is something new pollen is not always yellow in this tulip pollen is dark purple the tassels on corn have pollen producing stamens but no pistols wind carries the pollen to the silk which is part of the pistol and neither the tassels nor the silks have bright colored petals sometimes what we call a flower is really many tiny flowers in a clover blossom each part like the one pulled off is a complete flower a composite flower is made up of clusters of closely packed flowers the daisies are composite flowers with an outside row having large petals and many inner rows having tiny petals each of these parts is a complete flower the story of how plants reproduce is a story that may vary in some details from flower to flower but in its important steps the story is always the same for every fruit that forms there was once a pistol in a flower there was also a stamen bearing pollen either within that flower or another flower of the same kind a pollen from the stamen was transferred to the pistol to fertilize a flower after the petals withered or were shattered by the wind part of the fertilized flower lived on it live and brought forth the fruit within the fruit where the seeds that would bring forth new plants in another springtime yes the story of how plants reproduce is one of the most wonderful in nature and though we cannot fully explain it we can look forward to watching the story unfold when winter is over and the story begins again [Music]