What is the Difference Between Apothecium and Perithecium

The main difference between apothecium and perithecium is that apothecium is a disc-shaped ascocarp, whereas perithecium is a rounded or flask-shaped ascocarp.

Apothecium and perithecium are two spore-bearing structures produced by fungi. They are sessile and fleshy.       

Key Areas Covered

1. What is Ascocarp
– Definition, Structure, Function
2. What is Apothecium
– Definition, Structure, Function
3. What is Perithecium
– Definition, Structure, Function
4. Similarities Between Apothecium and Perithecium
– Outline of Common Features
5. Difference Between Apothecium and Perithecium
– Comparison of Key Differences

Key Terms 

Apothecium, Perithecium

What is Ascocarp

Ascocarp is the fruiting body of the Ascomycota, a phylum of fungi. It contains very tightly interwoven hyphae. Also, it contains four to eight ascospores and millions of embedded asci. Many ascocarps are bowl-shaped apothecia; some are spherical or flask-shaped perithecia with pore openings to release spores. Others are cleistothecia with no opening. Also, there are two types of ascocarps. It is epigeous when it grows above the ground, as in morels. Others are hypogeous and contain underground ascocarps, such as in truffles.

Figure 1: Ascomycota

In addition, Ascomycota is a phylum of the ascocarp-producing fungi. It is one of the largest and morphologically diverse groups of fungi. There are around 60,000 well-known species of Ascomycota. Significantly, the group contains the multicellular cup fungi. Half of the members of the phylum form lichens. Others form mycorrhizal relationships with plants. Very few of them are animal and plant pathogens.

Notably, the main characteristic feature of Ascomycota is the formation of four to eight sexual spores inside a microscopic sac called ascus. Hence, they are known as sac fungi. Ascocarps bear these asci. However, Ascomycota’s main form of reproduction is asexual reproduction, which occurs through the formation of numerous asexual spores called conidia. Generally, conidia are formed at the tips of fungal hyphae.

What is Apothecium

Apothecium is a wide and open spore-bearing structure that contains a saucer-shaped or cup-shaped fruit body. The three parts of the apothecium are hymenium, hypothecium, and excipulum. The hymenium is the upper concave surface that contains asci. Importantly, asci are freely exposed at maturity because the fertile layer is free. Therefore, many spores can disperse simultaneously.

Figure 2: Morchella 

Furthermore, apothecium occurs in the Dictyomycetes. Also, the morel of Morchella is an edible ascocarp, but it is not a mushroom. It contains a mass of apothecia fused into a single structure. Other genera that produce apothecium include Helvella and Gyromitra. 

What is Perithecium

Perithecium is a flask-shaped fruiting body that contains an apical pore called an ostiole. Ascospores escape through this pore. Periphyses are the hair-like structures that line the osmolar line. Perithecium contains unitunicate asci that are cylindrical. They occur on s stipe. Ascospores develop from the inner wall of the perithecium.

Figure 3: Hypocreales

Moreover, perithecium occurs in Hypocreales, Xylaria, Nectria, Claviceps, and Neurospora. 

Similarities Between Apothecium and Perithecium

• Apothecium and perithecium are two fruiting bodies that produce spores in fungi.
• They produce sessile and fleshy structures.
• Also, they contain asci arranged parallelly on the floor of the fruiting body. 

Difference Between Apothecium and Perithecium

Definition

Apothecium refers to a spore-bearing structure in many lichens and fungi consisting of a discoid or cupped body bearing asci on the exposed flat or concave surface. In contrast, perithecium refers to a spherical, cylindrical, or flask-shaped hollow fruiting body in various ascomycetous fungi containing the asci and usually opens by a terminal pore. 

Shape

Apothecium is a disc-shaped fruiting body, while perithecium is a rounded or flask-shaped fruiting body.

Hymenium Layer

Apothecium contains a top and opened hymenium layer, while perithecium contains an encased hymenium layer with an apical opening called an ostiole.

Conclusion

In brief, apothecium and perithecium are two structures of fruiting bodies in fungi. They contain asci that produce spores. Apothecium is a disc-shaped fruiting body where its hymenium layer occurs on the top. In comparison, perithecium is a rounded or flask-shaped fruiting body that contains an encased hymenium layer. Also, it contains an apical opening called the ostiole. Therefore, the main difference between apothecium and perithecium is their structure. 

References:

1. (2022a, May 4). 3.5.2: Types of ascocarps. Biology LibreTexts. 

Image Courtesy:

1. “Sarcoscypha coccinea – Ascomycete 00” By Guido Gerding – Own work (CC-BY SA 3.0) via Commons Wikimedia
2. “Morchella conica 1 beentree” By Beentree – Own Work (CC-BY SA 4.0) via Commons Wikimedia
3. “Cordyceps capitata” By Jason Hollinger (jason) – Own Work (CC-BY SA 3.0) via Commons Wikimedia