A Little Bit More
Dandelions are members of the largest of the plant families, Asteraceae (as-ter-A-ceh-ee). These flowers are often referred to as composites since many are composed of two kinds of miniature flowers – ray and disk. Although many of the plants in this family are considered weeds, like ragweed, thistles, and burdock, others are cultivated as food or beauty – chrysanthemums, marigolds, zinnias, sunflowers, lettuce, and artichokes. No matter where you live, even in urban areas, at some time during the year, one or more of these kinds of plants is bound to be growing near you.
The typical composite flower has a flowering head made up of many tiny flowers, all seated on the end of the stem. There are three basic flower “compositions” or arrangements that make up this family.
1. In this group, the flowering heads are made up of 2 kinds of flowers – tiny petals called disk flowers forming narrow tubes occupying the central part or disk, and an outer ring of flat blades or rays called ray flowers. Asters, sunflowers, daisies, sneezeweeds, chrysanthemums, and ragweeds are just some of these.
2. In the second group, there are no ray flowers on the head, just disk flowers. Ironweeds, thoroughworts, pussy-toes, and thistles make up this kind.
3. In the third group, the head is composed entirely of ray flowers. Chicories, hawkweeds, and dandelions make up these
Activities
Science – Flowers galore
Objectives: A better sense of what composite flowers are like
Materials: Reference material, paper and coloring materials
We’ve given you the 3 composite flower types and I think it would be fun and helpful for your students to look up photos of these flowers and draw and color them in. Make sure they list which one of the three they’re dealing with if they can.
Have students select just one or two flowers from a source of composite flowers, draw their flower, color their flower and then label that flower. If they can determine if this flower has both ray and disk flowers, only ray flower, or only disk flowers, they can note that too.
3 Basic Types of Composite Flowers – family Asteraceae (Composite family)
1. In this group, the flowering heads are made up of 2 kinds of flowers – tiny petals called disk flowers forming narrow tubes occupying the central part or disk, and an outer ring of flat blades or rays called ray flowers. Asters, sunflowers, daisies, sneezeweeds, chrysanthemums, and ragweeds are just some of these.
2. In the second group, there are no ray flowers on the head, just disk flowers. Ironweeds, thoroughworts, pussy-toes, and thistles make up this kind.
3. In the third group, the head is composed entirely of ray flowers. Chicories, hawkweeds, and dandelions make up these.
Good photos and illustrations of composites
More illustrations of composite flowers
family Asteraceae
Sunflower or Daisy Family
Key Concepts
Structures and Functions, Reproduction, Identification
Questions
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