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Many Devonian plants were seedless. Fern bear interesting traces of their origins. They produce no seeds but rather spore cells that fall to the soil and grow into a peculiar intergeneration plant that is not a leafy fern but a specialized fungu-like form that produces egg cells and sperm cells. Propelled by its whip-like tail, the sperm must swim a short distance through the water of moist soil to fertilize an egg cell from a neighboring plant. The fertilized egg then grows into a mature fern that produces more spores (in the brownish spots on the underside of fern leaves). It is as if the fern is an | ||
Figure 15 Fern Life-cycle [view large image] |
Figure 16 Devonian Plants [view large image] |
amphibian plant, growing on land but reverting to water to transmit its gametes. Figure 15 shows the life-cycle of ferns alternating between the haploid and diploid states. Ferns are |