Glossary of biological terms: M

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Massenerhebung effect. Depression of the altitudinal limit of montane forest on small mountains compared with large ones. See Grubb, P.J. 1971. Interpretation of the 'Massenerhebung' effect on tropical mountains. Nature 229: 44-45.

mitochondria

mycelium. A network of fungal hyphae (filaments) forming the vegetative part of a fungus.

mycorrhiza (pl. mycorrhizae). A mutualistic association between a fungus and the roots of a higher plant. About 85% of vascular plant species have mycorrhizae. The fungus benefits the plant by decomposing organic matter in the soil and providing minerals to the plant, and the plant benefits the fungus by providing sugars, amino acids, and some other organic substances. Two main types occur: (1) Endomycorrhizae. The fungus penetrates the cortical cells where it coils, or branches (the composite branching hyphae in a cell are collectively called an arbuscule); and (2) Ectomycorrhizae. The fungus forms a sheath around the roots with hyphae growing inbetween the cortical cells.