Yeast

A complex group of fungi resembling one another in existing as single cells that "bud" directly to form new cells. The colonies are pasty in appearance. Some yeasts may form ascospores within their cells. Common in moist habitats and often able to grow at reduced oxygen levels. Holomorphs various and not necessarily related to one another. Ref: Arx, Rodrigues de Miranda, Smith, and Yarrow 1977