‖ ascus Bot.
(ˈæskəs)
Pl. -i.
[mod.L., a. Gr. ἀσκός bag, sac.]
A membranous tubular cell, esp. the swollen sac-like cell at the end of the branches of the hyphæ in certain fungi and lichens, in which the reproductive sporules or sporidia develop.
| 1830 Lindley Nat. Syst. Bot. 332 These cases (thecæ) are..contained in other membranous cases (asci). 1875 Bennett & Dyer Sachs' Bot. 240 With the development and escape of the spores the ascus disappears. |