Apothecia and perithecia (from Albert Schneider's A text-book of general lichenology)
Apothecia and perithecia contain asci as well as sterile fungal hyphae (called paraphyses) growing between the asci.
1. Apothecium of Umbilicaria pustulata , showing two asci, each containing one large spore.
2. Two perithecia of Trypethelium virens . The very rudimentary thallus develops within bark, as do the perithecia. The drawing shows an immature perithecium (on the left) and a mature perithecium. 3.This shows a magnified view of some asci and branched paraphyses of Trypethelium virens . 4. Apothecium of Arthonia radiata .
Note: not all to the same scale
Albert Schneider's A text-book of general lichenology, published in Binghamton in 1897 by Willard N. Clute & Co. illustrates the structural features of various lichens from the north-eastern United States.