Lesson CXXXV

A Type Lesson for a Composite Flower

Leading thought—Many plants have their flowers set close together to make a mass of color, like the geraniums or the clovers. But there are other plants where the flowers of one flower-head act like the members of a family, those at the center doing a certain kind of work for the production of seed, and those around the edges doing another kind of work. The sunflower, goldenrod, asters, daisies, cone-flower, thistle, dandelion, burdock, everlasting, and many other common flowers have their blossoms arranged in this way. Before any of the wild-flower members of this family are studied, the lesson on the garden sunflower should be given. (See Lesson CLXII).

Method—These flowers may be studied in the schoolroom with suggestions for field observations. A lens is almost necessary for the study of most of these flowers.

Observations—

1. Can you see that what you call the flower consists of many flowers set together like a beautiful mosaic? Those at the center are called disk-flowers; those around the edges banner or ray-flowers.

2. Note that the flowers around the edges have differently shaped corollas than those at the center. How do they differ? Why should these be called the banner flowers? Why should they be called the ray-flowers? How many banner-flowers are there in the flower family you are studying? How are the banners arranged to make the flower-head more attractive? Cut off or pull out all the banner-flowers and see how the flower-head looks. What do the banner-flowers hold out their banners for? Is it to attract us or the insects? Has the banner-flower any stigma or stamens?

3. Study the flowers at the center. Are they open, or are they unfolded, buds? Can you make a sketch of how they are arranged? Are any of the florets open? What is the shape and the color of the corolla? Can you see the stamen-tubes pushing out from some? What color are the stamen-tubes? Can you see the two-parted stigmas in others? What color is the pollen? Do the florets at the center or at the outside of the disk open first? When they first open, do you see the stamen-tube or the stigma?

4. The flower-heads are protected before they open with overlapping bracts, which may be compared to a shingled house protecting the flower family. As the flower-head opens, these bracts are pushed back beneath it. Describe the shape of these bracts. Are they set in regular, overlapping rows? Are they rough or smooth? Do they end bluntly, with a short point, with a long point, with a spine, or a hook? How do the bracts act when the flower family goes to sleep? Do they remain after the seeds are ripened?

5. Take a flower-head apart, and examine the florets. Can you see what part of the floret will be the seed? Is there a fringe of pappus above it? If so, what will this be on the seed?

6. Study the ripe seeds. How are they scattered? Do they have balloons? Is the balloon close to the seed? Is it fastened to all parts of it?