THERE ARE EXOGENS AND ENDOGENS
THE PISTIL AND STAMENS OF THE LILY
"Now let us tell the parts of a flower. That was what we were doing when you came up," said Davy.
"And let me tell again," said little Prue. "I know I can get them right, this time."
So little Prue told again, and got it almost right, though she did call anthers "panthers" again, just as the first time.
"Now, Davy, it's your turn," said the Chief Gardener.
Davy picked up a little pink flower which he had found in the grass. It was oxalis, or sorrel, and sometimes the children nibbled the sour leaves, calling it sour-grass. Of course, you must not forget that Davy was older than Prue, and perhaps a little more thoughtful.
"This," he began, picking off the little green flower-casing, "is the calyx, and each little piece is called a sepal. This flower has five sepals in its calyx, and five petals in its corolla. These are the petals," and he pulled out the little pink flower-leaves, and laid them by the green sepals. Then he held it up for the Chief Gardener and little Prue to see.
"Look at the stamens," he said. "They all grow together at the bottom."
"That's because your sorrel is a Monadelphian," said the Chief Gardener.
Davy looked puzzled.
"I know what a Philadelphian is," said Prue.
Davy laughed.
"The words are very much alike," smiled the Chief Gardener. "They both mean brotherhood, and come from some old Greek words. Philadelphia means brotherly love, and Monadelphia means brotherly union. You see those stamens are all brothers and are joined together as one. All plants with such stamens are called Monadelphians."
"A stamen has three parts," Davy went on, "its filament, its anther, and its pollen. The filament is the stem, the anther is its cap, and the pollen is the dust which falls on the pistil and helps to make the seed."
A PISTIL AND CALYX AND A COMPLETE FLOWER
Very carefully Davy took away the ring of stamens, and left only the little yellowish-green center of the sorrel flower.
"This is where we get the seed," he said, as gravely as an old college professor lecturing to a class. "This is the pistil, and it has three parts, too: the pod, the style, and the stigma. The stigma is the little piece at the top which catches the pollen from the anthers. The style is the stem, and the pod is the big part below which holds the seeds."
He held up the little stripped flower again. "This pistil has five styles and five stigmas," he went on. "A good many flowers have more than one. It has ten stamens, too—two stamens for each style, and five petals and five sepals. You can divide it by five all the way through."
"Even to the seed-pod," added the Chief Gardener. "It has five divisions," and he cut the tiny green pulp and showed them with his magnifying-glass. "The little sorrel flower is one of the most perfect of flowers—one of the most perfect in a great class of flowers called Ex-o-gens. There is one other class called End-o-gens. Those words are from the Greek, too. Exogen means outward-growing. Endogen means inward-growing. The stem of an Exogen grows by layers, as most trees grow."
"Oh, yes," said Prue, "I know. We counted the rings on that big oak that was cut down over by the lake last year. It had one ring for each year."
"That's right, Prue, and the stem of the Endogen grows inside a shell, and is often just a soft pith, like the inside of a cornstalk. These are the two great classes of all flowering plants and trees. You can always tell the difference by their stems; nearly always from their leaves; always from their seeds, if you have a strong magnifying-glass, for the little germ of the Exogen has two leaves like the morning-glory, and the germ of the Endogen has but one like the lily, or corn. But the easiest way for you to tell is by the flowers. An Exogen flower nearly always goes by fives, like the little sorrel bloom, sometimes by fours, but hardly ever by threes. The Endogen flower is nearly always divided in threes, like the lily, which has six petals. It very seldom has four parts, and never five. So, you see, we know right away that the sorrel and the rose and buttercup are Exogens, and that the lily and the hyacinth and the daffodil are Endogens. Of course, there are many flowers not so easy to place as these, and I am afraid I am giving you too hard a lesson for one time, especially for such a hot day."
"But I'm not hot now," said Davy. "There's a fine breeze, and I like to sit here and talk." So they talked on about the different kinds and classes of plants, and by and by when big Prue found them, little Prue had much to tell her about all the new things she had learned. And she was careful not to pronounce anything wrong, and to explain that an Exogen was a plant that grew on the outside, and that an Endogen was another plant that grew on the inside, and big Prue said that Davy must be an Exogen, because he was getting so fat, and that little Prue must be an Endogen, because she was growing so smart. Then everything had to be told over, and then it was tea-time, with a dainty table all spread under the arbor, and delicious raspberries, and very, very delicious ice-cream.
A GROUP OF ENDOGENS—THE LILY, HYACINTH, AND DAFFODIL
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