ostiole (plural ostioles)
- (mycology) A small hole or opening through which certain fungi release their mature spores.
- 2010, Helen Gwynne-Vaughan, Fungi: Ascomycetes, Ustilaginales, Uredinales, page 54:
- The Erysiphacae may possibly have given rise to the Laboulbeniales, the only other group in which a single daughter cell of the oogonium is responsible for the asci, and perhaps to the lower Pyrenomycetes also; these, like the Erysiphaceae, have regularly arranged asci, and in Chaetomium fimete the perithecium is without an ostiole.
- (botany) A similar hole or opening in plants, such as the opening of the involuted fig inflorescence through which fig wasps enter to pollinate and breed.