Handbook of Nature-Study · Lesson CXXXV · Topic 21: Flower families: the composites
135. A type lesson for a composite flower
Goal: Your child discovers that a daisy-like “flower” is really a family of many tiny flowers: disk-flowers in the middle and banner (ray) flowers around the edge.
You'll need
- Nature notebook, pencil and colored pencils
- A hand lens (magnifying glass)
- Two or three daisy-type flowers: a garden sunflower, black-eyed Susan, aster or daisy
- A toothpick
- White paper
What's in the book
No Teacher's Story: this is Comstock's outline for studying any flower of the daisy family. Leading thought, Method and six questions. Later lessons (goldenrod, asters, daisy, black-eyed Susan, thistle, dandelion and others) send you back to it.
The lesson, step by step
When and where
Late summer and fall are best, when sunflowers, asters, black-eyed Susans and goldenrod are all in bloom. Comstock says to give the garden sunflower lesson first; in this book it is Lesson CLX, so you may want to do that one now and come back.
The 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.
A family, not one flower
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.
Pick out one disk-flower with the toothpick and put it on white paper. Look at it with the lens. It is a whole flower, with its own tiny tube.
The banners
Note that the flowers around the edges have differently shaped corollas than those at the center. How do they differ?
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?
Which open first?
Do the florets at the center or at the outside of the disk open first?
Look for a ring of open florets with buds still closed in the middle.
The shingled house
The flower-heads are protected before they open with overlapping bracts, which may be compared to a shingled house protecting the flower family.
Turn the flower-head over and look at the bracts underneath. Are they in rows like shingles?
Seeds
Study the ripe seeds. How are they scattered?
Think of the dandelion's parachutes and the thistle's down.
Nature notebook
Draw the flower-head from above, then one disk-flower and one banner-flower enlarged beside it. Label them. Keep this page: you'll use it for the next few lessons.
Afterwards
Find three different daisy-family flowers this week and check each one against this outline.
Tip
Comstock's text sends you to “Lesson CLXII” for the sunflower, but in this edition the sunflower lesson is numbered CLX.
Answers to the book's problems
The banner (ray) flowers around the edge have a long, flat, strap-shaped corolla; the disk-flowers in the center are small tubes. The banners attract insects. The outer disk-flowers open first and the blossoming moves inward. The overlapping bracts underneath are called the involucre.
Worked out for this site from the scan. If a number in your copy differs, trust the book.