Page:Parsons How to Know the Ferns 7th ed.djvu/60

 prothallium (Fig. 8). This is connected with the soil by hair-like roots. On its lower surface are borne usually both the reproductive organs of the fern, the antheridia, corresponding to the stamens or fertilizing organs of the flower, and the archegonia, performing the office of the flower's pistils, inasmuch as their germ-cells receive the fertilizing substance produced by the antheridia. But no seeds are formed as the result of this fertilization. Instead of this seed-formation which we note in the flowering plant, the germ-cell in the fern develops into a fern-plant, which forms the "asexual" generation.

The first fronds of this little plant are very small and simple, quite unlike the later ones. For a time the plant is nourished by the prothallium, but as soon as it is sufficiently developed and vigorous enough to shift for itself, the prothallium dies away, and the fern maintains an independent existence.

Eventually it produces fronds which bear on their lower surfaces the sporangia containing the minute spores from which spring the prothallia.

For our present purpose it is enough to say that spores differ from seeds in that they are not the immediate result of the interaction of reproductive