Molds are fungi that grow in the form of multicellular filaments called hyphae. Some molds cause or food spoilage; others play an important role in biodegradation or in the production of various foods, beverages, antibiotics and enzymes.

One of the most common ferns -  Dryopteris filix-mas occurring throughout much of Europe, Asia and North America. This one is from  a forest near Warsaw. On the abaxial surface of the mature blade  you can find sori in two rows. When the spores  ripen  the indusium start to shrivel, leading to the release of the spores -  a reproductive structures.