What is an indusium in a fern?
What is an indusium in a fern? A flap of tissue that protects the sori in some ferns. This can take a variety of forms. When spores are mature and ready for release, the indusia usually shrivel or bend backwards to expose the sporangia. Occasionally, if the indusia completely cover the sporangia. they may tear irregularly. What is the function of the indusium? In many genera, the sporangia are covered by an indusium. This is a specialized outgrowth of the leaf that functions in protection of the sporangia. This often has the shape of an upside down umbrella and shrivels...