Handbook of Nature-Study · Lesson CXXX · Topic 20: Summer wildflowers, climbers and water plants
130. The dodder
Goal: Your child examines dodder, a leafless orange vine, and explains how a parasite steals its living from another plant.
You'll need
- Nature notebook, pencil and colored pencils
- A hand lens (magnifying glass)
- A paper bag
What's in the book
A Teacher's Story about the dodder and the lesson: Leading thought, Method and five questions, followed by a quotation from L. H. Bailey about teaching.
The lesson, step by step
When and where
Look in late summer for tangles of orange or yellow threads over weeds and plants in fields, roadsides and damp places. Dodder has no green leaves.
The leading thought
There are some plants which not only depend upon other plants to hold them up, but they suck the life-juice from these plants and thus they steal their living.
The stem
What is the color of the stem? In which direction does it wind?
How is the stem fastened to the host plant?
Pull back a short piece and look with the lens where it was attached. You may see little bumps (suckers) and marks on the host stem.
No leaves?
How does the dodder get hold of its victim? Has the dodder any leaves of its own? How can it get along and grow without leaves?
SayGreen leaves make food from sunlight. Dodder has none, so it takes food from the host plant instead. That is what a parasite does.
Flowers and seeds
How do the flowers look through a lens? Are there many flowers?
How many seeds does each flower develop? How do the seeds look? In what way are they a danger to our agriculture?
Nature notebook
Draw a host plant with dodder wound around it, and a close-up of the tiny flower cluster. Label host and parasite. If you find dodder in your own garden, put it in a bag in the trash, not the compost. Wash hands when you come in.
Tip
The quotation after this lesson is worth reading yourself: Bailey says nature-study is not mainly telling children facts but setting them to find things out.
Answers to the book's problems
Dodder has no green leaves, so it cannot make its own food; it gets food from the host through its suckers. Each flower ripens four seeds. Dodder seeds get harvested with clover and other crop seed, so farmers sow the enemy along with the crop.
Worked out for this site from the scan. If a number in your copy differs, trust the book.