Jimmy Bush, age 12, of Georgiana, Ala.) for his question:

HOW DO FERNS REPRODUCE?

Nowadays there is talk of a generation gap. True, parents and children have their differences, but first  and second generation humans are basically alike. This is not so in the fern world. There the first and second generations are quite different plants.

The lovely lacy ferns were among the earliest plants, designed long before the flowering plants arrived with their simplified method of reproduction by seeds. The fern's complex method is called alternation of generation  which means that its life cycle develops through two different plant forms.

The two generation story begins on the underside of a leafy fern frond. When time comes to multiply, it produces rows of little brownish buttons. These are packages of tiny spores that crack open when the spores are ripe. This original parent plant is the sporophyte generation, and when its spores are scattered its duty is done.

Here and there a lucky spore lands in a shady spot on some moist soil. It sets down threads to soak up moisture and sprouts a heart shape top about a half an inch wide. This is the gametophyte generation, and its duty is _o produce fertilized seeds. It is called a prothallus, and both male and female plant cells develop on the underside of its leafy heart.

On a mild morning, when the forest floor is damp with dew, the male cells break free and glide through the moisture. The lucky one reaches a female cell, producing a fertilized egg cell. This completes the duty of the gametophyte generation. The fertile cell is called a zygote, and right there on the little heart shape prothallus it multiplies by dividing itself again and again.

Its cells contain the blueprint for its future growth. It sets down stringy roots and coiled stems that open up and become lacy fern fronds. Obviously it is a perfect copy of the original parent fern  and the alternation of generations is complete.

The average fern does not depend entirely on this complex method of reproduction. As a rule, its rhizome type root is just below the surface. Sometimes a new parent fern sprouts from a node in a trailing rhizome. In some ferns, the tip of a frond can dip down to the soil and sprout a new parent plant.