Fungi, division of simple plants that lack chlorophyll, true
stems, roots, and leaves. Unlike algae, fungi cannot
photosynthesize, and live as parasites or saprophytes. The
division comprises the slime molds and true fungi. True
fungi are multicellular (with the exception of yeasts); the
body of most true fungi consists of slender cottony
filaments, or hyphae. All fungi are capable of asexual
reproduction by cell division, budding, fragmentation, or
spores. Those that reproduce sexually alternate a sexual
generation (gametophyte) with a spore-producing one. The
four classes of true fungi are the algaelike fungi (e.g.,
black bread mold and downy mildew), sac fungi (e.g., yeasts,
powdery mildews, truffles, and blue and green molds such as
Penicillium), basidium fungi (e.g., mushrooms and puffballs)
and imperfect fungi (e.g., species that cause athlete's foot
and ringworm). Fungi help decompose organic matter (important
in soil renewal); are valuable as a source of antibiotics,
vitamins, and various chemicals; and for their role in
fermentation, e.g., in bread and alcoholic beverage
production.
[ The Concise Columbia Encyclopedia ]