leptosporangium

A leptosporangium is a type of sporangium, which is a structure that produces spores in plants like ferns. Specifically, leptosporangia are distinguished by originating from a single cell and having a thin, one-layered wall. This contrasts with eusporangia, which develop from multiple cells and have thicker walls.12

Leptosporangia are characteristic of the majority of fern species in the class Polypodiopsida. They often possess a specialized structure called an annulus, which is a row of thickened cells that aids in the explosive release of spores. These spore-producing structures are typically found on the undersides of fern fronds, often clustered together in sori.134