Their remains later became the major consituent in coal. The stobilus produces spores that germinate to form tiny, haploid gametophytes. Spores used as flash powder and coagulant. The fern you see is usually just the leaf or frond . The stem is underground and is called a rhizome .
Spores germinate to form a tiny, heart-shaped gametophyte .
Fertilization still requires water, because the sperm must swim to a gametophyte bearing an egg. Once fertilization occurs, the zygote grows into the diploid sporophyte. The female gametophyte is as few as 7 cells and is housed in a structure called an ovule . Pollination takes place in spring. Once pollen lands on a female cone, it closes up and the pollen tube grows for 12-15 months before reaching the female gametophyte in the ovule.