noun
definition
An ascocarp shaped like a skittle or ball, distinguished by a small pore, the ostiole, through which the spores are released one by one when ripe.
Examples of perithecium in a Sentence
Ascus from perithecium containing six spores, X30o.
We find two chief types of fruit bodies in the lichens, the perithecium and apothecium; the first when the fungal element is a member of the Pyrenomycetes division of the Ascomycetes, the second when the fungus belongs to the Discomycetes division.
The perithecium is very constant in form and since the gonidia take no part variations are of value in classification some more details may be added.
The Ascolichenes are again divided into Pyrenocarpeae or Pyrenolichenes and Gymnocarpeae or Discolichenes; the first having an ascocarp of the nature of a perithecium, the second bearing their ascospores in an open apothecium.
Perithecium simple not divided.
Whether a true sexual process precedes these processes or not does not affect the present question, the point being that the resulting spheroidal "fructification" (cleistocarp, perithecium) has a definite wall of its own not directly comparable with a stroma.
These three elements - trichogyne, trichophoric cell, and carpogenic cell - are regarded as the procarp. The spermatia have been shown by Thaxter to fuse with the trichogyne, after which the axial cell below (carpogenic cell) undergoes divisions, and ultimately forms asci containing ascospores, while cells investing this form a perithecium, the whole structure reminding us essentially of the fructification of a Pyrenomycete.
Part of a crushed perithecium of Sordaria, showing several asci containing 8 ascospores.