In most fungi the vegetative system for exploitation of the substrate is composed of thread-like filaments called hyphae. In Yeast fungi, however, the vegetative system is composed of single cells. These reproduce by a method called budding. A blip at one or both ends (and sometimes from the sides) of a cell grows out and enlarges until it is as large as the parent cell; then it breaks away. The process is repeated again and again. Yeasts do best in free water or in very moist environments.