leptosporangium

plural leptosporangia

1. biologyA sporangium formed from a single epidermal cell.

   2003, Jill Bailey, Filicinophyta (ferns), entry in The Facts on File Dictionary of Botany, page 84, In the Filicales the leptosporangium has a specialized spore dispersal mechanism involving an annulus of cells with thick walls that ejects spores explosively as it dries out.

   2 more examples

   The characteristic that unites the Filicales as a monophyletic clade is the presence of leptosporangia with an annulus-an area of specialized cells involved in dehiscence.[…]Leptosporangia typically produce only a few spores, and are most commonly homosporous.

   2010, Lily Bora, Principles of Paleobotany, page 256

   Leptosporangia are unique among vascular plants in (1) developing from a single cell, and (2) having a single layer of cells making up the sporangium wall.

   2011, Michael G. Simpson, Plant Systematics, page 88