REPRODUCTION
Ferns are propagated in various ways. A frequent method is by perennial rootstocks, which often creep beneath the surface, sending up, it may be, single fronds, as in the common bracken, or graceful leaf-crowns, as in the cinnamon fern. The bladder fern is propagated in part from its bulblets, while the walking leaf bends over to the earth and roots at the tip.
[Illustration: MALE SHIELD FERN. Fern Reproduction by the Prothallium]
Ferns are also reproduced by spores, a process mysterious and marvellous as a fairy tale. Instead of seeds the fern produces spores, which are little one-celled bodies without an embryo and may be likened to buds. A spore falls upon damp soil and germinates, producing a small, green, shield-shaped patch much smaller than a dime, which is called a prothállium (or prothallus). On its under surface delicate root hairs grow to give it stability and nutriment; also two sorts of reproductive organs known as antherídia and archegònia, the male and female growths analogous to the stamens and pistils in flowers. From the former spring small, active, spiral bodies called ántherozòids, which lash about in the moisture of the prothállium until they find the archegònia, the cells of which are so arranged in each case as to form a tube around the central cell, which is called the òösphere, or egg-cell, the point to be fertilized. When one of the entering ántherozòids reaches this point the desired change is effected, and the canal of the archegònium closes. The empty òösphere becomes the quickened òösphore whose newly begotten plant germ unfolds normally by the multiplication of cells that become, in turn, root, stem, first leaf, etc., while the prothállium no longer needed to sustain its offspring withers away.[1]
[Footnote 1: In the accompanying illustration, it should be remembered that the reproductive parts of a fern are microscopic and cannot be seen by the naked eye.]
Fern plants have been known to spring directly from the prothállus by a budding process apart from the organs of fertilization, showing that Nature "fulfills herself in many ways."[2]