from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A membranous, often club-shaped structure in which typically eight ascospores are formed through sexual reproduction of ascomycetes.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A sac-shaped cell present in ascomycete fungi; it is a reproductive cell in which meiosis and an additional cell division produce eight spores.
from the GNU version of the Collaborative International Dictionary of English
- n. A small membranous bladder or tube in which are inclosed the seedlike reproductive particles or sporules of lichens and certain fungi.
from The Century Dictionary and Cyclopedia
- n. In botany, the spore-case of lichens and ascomycetous fungi, consisting of a single cell, usually the swollen terminal cell of a branch of a hypha, from the protoplasm of which the spores (typically 8) are produced. Also called ascidium and theca.
- n. In archœol., same as askos.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. saclike structure in which ascospores are formed through sexual reproduction of ascomycetes
The mildews may be divided into two genera: _Podosphæra_, with a single ascus in the spore fruit; and _Erysiphe_, with two or more.
For instance, in the asci of lichens there are formed from a portion of the protoplasm four or more small ascospores, which secrete a cell-wall and lie loose in the ascus.
They are set free by the rupture of the ascus, and germinate by putting out through their walls one or more filaments which branch and form the thallus of a new individual.
An ascus of _Buella parasema_, containing 8 spores.
Thallus granulose to verrucose and subareolate, sometimes inconspicuous and evanescent; apothecia minute to middle-sized, adnate or more or less immersed, exciple usually prominent and persistent, but sometimes becoming covered, disk flat to convex; hypothecium and hymenium pale to brown; spores simple, hyaline, minute, numerous in each ascus.
Spores minute, numerous in each ascus _Biatorella_, p. Spores larger, usually 8 in each ascus,
In this group, however, the spores are borne inside of club-shaped bodies, called sacs or asci (singular, ascus).
[F] The sub-class Ascomycetes includes the morels, helvellas, cup fungi, etc., and many microscopic forms, in which the spores are borne inside a club-shaped body, the ascus.
In the latter species there are only two spores in an ascus.
This fungus projects eight spores at once using a spray of fluid from the plant's spore-bearing cells, which make up the ascus.