192 



Planli — Our Livinfi Resiniices 



For further information: 



Amy Y. Rossman 



U.S. Department of Agriculture 



U.S. National Fungus Collections 



Beltsville, MD 2070? 



Farr, D., G. Bills. G. Chamuris, and A. Rossman 1989. 



Fungi on plants and plant products in the United States. 



American Phytopathological Society Press. St. Paul. 



MN. 1.152 pp. 

 Hawksworth. D.L. 199|, The fungal dimension of biodiver- 

 sity: magnitude, significance, and conservation. 



Mycological Res. 95:641-6.?5. 

 Jong. S.C.. and M.J. Edwards. 1991. American type culture 



collection catalogue of tllamentous fungi. 18th ed. 



Rockville. MD. 667 pp. 

 Large, E.G. 1962. Ad\ance of the fungi. Dover, New York. 



488 pp. 



Redlin. S.C. 1991. Disciila deslnictiva sp. nov., cause of 

 dogwood anthracnose. Mycologia 83:633-642. 



Reed.V.E. and D.E Farr. 1993. Index to Saccardo's Sylloge 

 Fungorum. Volumes I-XXVI IN XXIX 1882-1972. Reed 

 Herharium. Darlington. MD. 884 pp. 



Rensberger. B. 1992. Underground goliath. Michigan mush- 

 room over 1.500 years old. Washington Post. April 2. 



Rossman. AY. 1994. A strategy for an all-taxa inventory of 

 fungal biodiversity. In C.I. Peng. ed. Biodiversity and ter- 

 restrial ecosystems. Bull, of the Academy Sinica Institute 

 Botany. In press. 



Macrofungi 



by 



Gregory M. Mueller 

 The Field Museum, Chicago 



Fig. 1. Enroloma sahnoneum. The 

 salmon-colored entoloma is a 

 common recycler of forest litter in 

 North American forests. 



Macrofungi are a diverse, commonly 

 encountered, and ecologically important group 

 of organisms. Like most fungi, the major part of 

 these organisms consists of a mass of thin, 

 microscopic threads (termed mycelium) grow- 

 ing in soil, decomposing leaves, and other sub- 

 strate. They differ from other fungi by forming 

 large, macroscopic fruitbodies at some time in 

 their life; the mushrooms sold in grocery stores 

 are an example of these fruitbodies. This group 

 of fungi includes all mushrooms (Fig. I), 

 morels, puffballs, bracket fungi, and cup fungi. 



Macrofungi are vitally significant in forests: 

 many species help break down dead organic 

 material, such as dead tree trunks and leaves. 

 into simple compounds usable by growing 

 plants. Thus, they act as nature's recyclers, 

 without which forests could not function. Some 

 species are major plant pathogens (causes of 

 disease) that cause millions of dollars of dam- 

 age to U.S. forests each year. Still other species 

 enter into a necessary, mutually beneficial asso- 

 ciation with trees such as oaks, pines, firs, and 

 spruces. In this association (Fig. 2). termed 

 mycorrhizae. the mycelium of the fungus brings 

 water and nutrients to the tree in return for tak- 

 ing excess food from the tree. Neither the tree 

 nor the fungus can survive without the other. 

 Finally, some of these fungi form an important 

 part of the diet of many small mammals and 

 insects. For example, small truffle-like fungi are 

 a major food source of the northern flying squir- 

 rel (Glaucomys sabrinus: see box). Because 

 macrofungi are an indispensable component of 

 the forest ecosystem, information on which 

 fungi occur in the forests and on the specific 



Fig. 2. Mycorrhizae formed 

 between ponderosa pine and 

 Laccaria laccata in the laboratory. 

 Note the branched pine roots and 

 threadlike fungal hyphae. 



role that they play is necessary for management 

 and maintenance of our forests. 



Macrofungi also directly affect people. 

 Though some fungi are deadly poisonous, oth- 

 ers are prized as edibles. Commercial mush- 

 room harvesting is a multimillion-dollar-a-year 

 business in the United States: for example, the 

 industry added an estimated $40 million to the 

 Oregon economy in 1993 alone. Additionally, 

 several thousand amateur mushroom hunters in 

 the United States collect solely for their own 

 enjoyment. 



Number of Species 



Considering the human, ecological, and eco- 

 nomic importance of these organisms, it is 

 somewhat surprising that there is not a good 

 estimate of the number of species of macrofun- 

 gi that occur in North America. Because there 

 are neither checklists of North American mush- 

 rooms and their relatives nor coinprehensive 

 regional treatments, the best estimates of North 

 American diversity are based on comparisons 

 with numbers of these organisms reported from 

 Europe. More than 3,000 species of mushrooms 

 and their relatives are reported from western 

 Europe (Moser 1983), but most scientists who 

 study fungi (mycologists) would estimate that 

 far more species occur in North America. For 

 example, more than twice as many species of 

 Lciciciriiis. Amanita, and Clitocyhe are reported 

 from the continental United States (Hesler and 

 Smith 1979; Bigelow 1982, 1985; Jenkins 

 1986) than from western Europe (Moser 1983). 



Better estimates exist for species diversity of 

 the other groups of North American macrofun- 

 gi. Gilbeitson and Ryvarden ( 1986, 1987) treat- 

 ed more than 400 species of polypore fungi. 

 Smith et al. ( 1981 ) listed nearly 300 species of 

 pufttalls and relatives, and Seaver ( 1942. 195 1 ) 

 covered more than 350 species of cup fungi and 

 other macro ascomycetes. Based on these data. 

 it is reasonable to predict that there are 5,000- 

 10.000 species of macrofungi in the United 

 States. A compilation of herbarium records in 

 U.S. and Canadian museums and universities 

 would provide a good first step in predicting the 

 diversity of these organisms. 



