eusporangium

A eusporangium is a type of spore-producing structure found in certain plants, primarily ferns. Unlike leptosporangia, which develop from a single cell, eusporangia arise from a group of cells. These structures are typically larger and have a thicker wall composed of two or more layers of cells. Eusporangia are characteristic of primitive fern groups such as the Psilotopsida and Marattiopsida classes. The opening mechanism of eusporangia is less specialized than that of leptosporangia; they release spores through a generalized stress on drying walls, without a specific mechanism to actively throw them.12