Fungi are living organisms that are distntly related to plants, and more closely related to animals, but rather different from either of those groups. Kingdom Fungi includes mushrooms, rusts, smuts, puffballs, truffles, morels, molds, and yeasts, and thousands of other organisms and microorganisms. Fungi grow best where there is a rich supply of organic matter. Most fungi are saprobic (obtaining nutrients from dead organic matter). Sincé they lack photosynthetic pigments, fungi cannot perform photosynthesis and must obtain their nutrients from preformed organic matter). They are therefore chemoheterotrophic organisms. Fungi reproduce sexually or asexually, or both, depending upon the species and the environmental conditions. As the name implies, sexual reproduction is the result of the unión of two spores. Most fungi reproduce both sexually an asexually. Asexual reproduction occurs in the fungi when spores form by mitosis. These spores can be conidia, sporangiospores, arthrospores (fragments of hyphae), or chlamydospores (spores with thick walls). Fungal spores are important in the identification of the fungus, since the spores are unique in shape, color, and size. A single spore is capable of germinating and reestablishing the entire mycelium. Spores are also the method for spreading fungi in the environment. Fungi grow well under the same conditions that favor the growth of bacteria --warmth and moisture. It is for this reason that fungal infections pose a serious problema to tropos in the tropics. As the temperatura decreases, fungal activity also decreastes; however, the spores are very resistant to cold, some surviving freezing temperaturas for long periods of time. On the other hand, fungi are esaily killed at high temperatures.