The Study of Plant Life

by Marie Carmichael Stopes

Fig. 129. A Prothallium (p), with a young Fern (f) growing out from it. (Magnified).

Some ferns take a short cut, and bear little ones directly on their leaves without any prothallium. You see this in the “Hundreds and Thousands” fern, where the old plant is sometimes covered over with little ones, which will grow if they are taken off and planted carefully.

Sometimes people are deceived by what is called the “flowering fern,” and expect that it will have flowers. In this fern we find that all the spore-cases grow together on a special leaf, which is so covered by them that it looks quite different from a usual one, and is called the flower, though it is not one. In all other ways the story of the spore building and growth is like that of usual ferns.

In our study of ferns, you see that they have many characters which are exceedingly different from either the flowering plants or pine-trees. In fact, they are so different that we require to add some new points to our list of characters for family divisions, which are:—

7. Instead of flowers there are little spore-cases, which contain a number of simple one-celled spores. These are generally found on leaves which are otherwise like the rest of the leaves of the plant.

8. Each spore grows out to form a small green structure, which differs from the parent, and which we call the prothallium.

9. The new fern-plant grows at first attached to the prothallium, but soon grows out beyond it, and is quite independent.

What we call “ferns” are not the only plants which belong to this big family, for the club-mosses and also the horsetails have almost the same arrangement for their building of new plants. Our character-points (7) (8) and (9) apply to them, even though the rest of their structures appear to be so different from the ferns. They are, therefore, put in the same big family with the ferns, though they have smaller classes for themselves apart from the true ferns.

Neither the ferns nor their near relatives are very important in the vegetation of to-day, but very long ago they were among the chief plants in the world, and grew to be as big as forest trees. Even then, however, they had almost the same way of forming spores that they have to-day, a fact which still marks them out as a family different from all the other families of plants.