Rhytisma
Rhytisma is a genus of fungi in the family Rhytismataceae. These fungi are plant pathogens that cause tar spot diseases on various trees and shrubs. They are characterized by their distinctive black, tarry-like fruiting bodies, known as stromata. While they are often found on leaves, they can also grow on stems and twigs.
Common Names
Species within the Rhytisma genus are commonly known as tar spots, especially when referring to their effects on trees and shrubs.
Characteristics
Rhytisma fungi are obligate parasites, meaning they require a living host plant to survive. They are also biotrophs, which means they obtain their nutrients from living plant cells. The fruiting bodies, or stromata, of Rhytisma are typically black and tar-like, and they can range in size from a few millimeters to several centimeters in diameter. These stromata are often raised above the surface of the leaf and can be quite conspicuous.
One distinctive feature of Rhytisma is the presence of perithecia, which are flask-shaped structures containing asci, the sac-like cells that produce spores. These spores are typically black and ellipsoidal.
Environments
Rhytisma fungi are found in a variety of temperate climates, primarily in forests and woodlands. They infect a wide range of host plants, including maples, oaks, sycamores, and birches. These fungi are particularly common in areas with high humidity and moisture.
References
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