DR KEITH WHEELER / SCIENCE PHOTO LIBRARY DR KEITH WHEELER / SCIENCE PHOTO LIBRARY
Fern sporocarp. Light micrograph of a transverse section through a sporocarp from a Marsilea fern. This section reveals two rows (pink stripes) of sori, structures that produces the spores. The sporocarp has a hard covering (brown) and is found at the base of the leaf stalk. There are two kinds of spores (several at centre): female megaspores (pink large balls) and male microspores (small red balls). These are released and germinate in water, with both male and female spores going through a succession of developmental stages that culminates in fertilisation. Magnification: x13 when printed at 10 centimetres wide.
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