Lesson CLXXVII

The Field Horsetail

The Fertile Plant

Leading thought—The horsetail is a plant that develops spores instead of seeds, and has green stems instead of leaves.

Method—In April and May, when the children are looking for flowers, they will find some of these weird looking plants. These should be brought to the schoolroom and the observation lesson given there.

Observations—1. Where are these plants found? On what kind of soil?

2. In what respect does this plant differ from other plants in appearance? Can you find any green part to it?

3. What color is the stem? Is it the same size its whole length? Is it smooth or rough?

4. Do you see any leaves on the stems? Do you see the black-pointed scales? In which direction do these scales point? Are they united at the bottom? What sort of a ring do they make around the stem? Split a stem lengthwise and see if there are joints, or nodes, where the ring joins the stalk.

5. How does the “blossom” look? What color are the little discs that make up the blossom? How are the discs set?

6. Take one of the plants which has the discs surrounded by green ridges. Shake it over a white paper. What comes from it? Where does it come from? Which discs on the stalk shed the green spores first?

The Sterile Plants

Leading thought—The horsetail or Equicetum is nourished by very different looking stems than those which bore the spores. It lacks leaves, but its branches are green and do the work of making food for the plant.

Method—The sterile plants of the horsetail do not appear for several weeks after the fertile ones; they are much more numerous, and do not resemble the fertile plants in form or color. These sterile plants may be used for a lesson in September or October. Some of these plants with their roots may be brought into the schoolroom for study.

Observations—1. Has this plant any leaves? How does it make and digest its food without leaves? What part of it is green? Wherever there is green in a plant, there is the chlorophyl-factory for making food. In the horsetail, then, what part of the plant does the work of leaves?

2. Take off one little branch and study with the lens. How does it look? Pull it apart. Where does it break easily? How many joints, or nodes, are there in the branch?

3. Study the socket from which one of the segments was pulled off. What do you see around its edge? How many of these points? Look at the branch in cross section. How many angles has it? What relation do the points bear to the angles? Do you think these points are all there are left of true leaves?

4. How do the little green branches come off the main stem? How many in a place? How many whorls of branches on the main stem?

5. Study the bases of the branches. What do you see? Look directly above where the whorl of branches comes off the main stem. What do you see? Cut the main stem in cross-section just below this place, and see if there are as many little points as there are angles, or ridges, in the stem. Do you suppose these little points are the remnants of leaves on the main stem?

6. What kind of root has the horsetail? Do you think this long running root is the true root or an underground stem? Where are the true roots? Do you think the rootstock dies off at the oldest end each year, like the fern? Can you find the little tubers in the rootstock, which contain nourishment for next year’s spore-bearing stalks?