Final answer:
The unique aspect of cup fungi (Ascomycota), to which Penicillium notatum belongs, is their unique method of sexual reproduction involving the production of conidia. They also often engage in mutualistic relationships, which is beneficial to both the fungi and their hosts.
Step-by-step explanation:
The unique aspect of the group of fungi to which Penicillium notatum belongs, typically known as cup fungi or Ascomycota, is their method of reproduction. Ascomycetes are distinct because they reproduce primarily through a sexual process that involves the production of specialized hyphal branches that form small propagules called conidia. These reproductive structures are usually conspicuously shaped like cups which help to disperse spores. Unlike many other fungi, Ascomycetes have septate hyphae, composed of cells each containing a single haploid nucleus.
Additionally, Ascomycetes often live mutualistically with other organisms. This mutualism results in a symbiotic relationship where both the fungus and its host benefit. For example, many Ascomycetes form lichens with algae or cyanobacteria, which are critical in many ecosystems for their role in soil formation and providing nutrients.