Another species of Rhizopus is used in the commercial production of glucocorticoids . Many mycorrhizal fungi belong to this group. The chestnut blight, which in a few decades killed almost all of the mature American chestnut trees in the Appalachians of North America. The Dutch elm disease, which has killed many of the American elms in the United States. The truffle and the morel , both highly-prized food delicacies.
Truffles establish a symbiotic relationship with the roots of such trees as oaks.
Saccharomyces cerevisiae one of the budding yeasts . Baker's yeast is also used in the commercial production of some vitamins. The fungal partner in most lichens is an ascomycete. Mushrooms are masses of interwoven hyphae growing up from the main mass of the mycelium growing underground. A single mycelium may expand outward year after year as its hyphae grow into new terrain.