indusium

plant anatomy

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June 29, 2026

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The indusium is a protective covering found in some ferns that shields their spore-producing structures, called sporangia. This covering can be a separate, unique formation, often papery, or it can be a rolled-over leaf margin, known as a false indusium. The true indusium's origins are not fully understood, but it can take various shapes, such as a cup that encloses the sorus or a two-lipped structure. These coverings help protect the sporangia from drying out and other environmental hazards.123

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fern
The indusium
Protection of the sporangial cluster from exposure, drying, and other hazards is accomplished in various ways, such as by the formation of the sori in grooves or pockets or by the production of various forms of covers. One is the so-called false indusium, a…
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Protection of the sporangial cluster from exposure, drying, and other hazards is accomplished in various ways, such as by the formation of the sori in grooves or pockets or by the production of various forms of covers. One is the so-called false indusium, a…
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sorus
…flap of tissue called an indusium. In rust and smut fungi, a sorus is a spore mass produced on the leaf of an infected plant. Reproductive structures called sori also occur in various species of marine algae. See also spore.
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…flap of tissue called an indusium. In rust and smut fungi, a sorus is a spore mass produced on the leaf of an infected plant. Reproductive structures called sori also occur in various species of marine algae. See also spore.
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