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Analysis of airflow patterns around models of mushrooms and fresh fruiting bodies in a low speed wind tunnel showed division of the airstream at the leading edge of the cap, an increase in wind speed a few millimeters above and below the cap, and the development of a mantle of very slow-moving air closer to the lower surface. Mushroom caps with a pronounced bell shape offered the greatest interrup- tion to airflow and showed the maximum reduction in wind speed beneath their lower surface. Calcula- tions suggest that the measured decrease in wind speed may reduce the number of spores that are blown back into the cap, promoting dispersal from the fruiting body.

Melanins are complex black polymers of resonance stabilized cyclic subunits (including in- doles, phenols, hydroxynaphthalenes) and are noto- riously intractable to chemical analysis. Cell walls of numerous fungi are melanized, rendering many spores, vegetative hyphae, and certain fruit bodies opaque. Melanin deposition protects the pigmented cell from physical and biological stresses, excludes poisons, and helps limit leakage of certain metabo- lites. By forming a physical barrier between the cell and its surroundings, the production of a melanized wall layer has a profound effect upon the interactions between pathogenic fungi and their hosts. In many plant and animal diseases caused by melanotic fungi, melanin biosynthesis is an important determinant of pathogenicity and virulence. The mode of action of melanin in these diseases is the subject of intensive research, and a variety of mechanisms that link fun- gal melanin and disease have been discovered.

Temperature measurements from the spore-producing gills, spines, and tubes underneath fruit-body caps revealed cooling in 18 basidiomycete species growing in mixed deciduous woodland. The temperature of cultured fruit bodies of Lentinula edodes and Pleurotus ostreatus fell upon exposure to low velocity airflow, consistent with an evaporative mechanism of cooling. The mechanism of ballistospore discharge characteristic of basidiomycete fungi is dependent on condensation of water from the air surrounding the spores onto the spore surface. The current model for this process predicts that condensation, and therefore spore discharge, is enhanced by cooling of the fruit body.

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