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Related to mycorrhiza: Arbuscular mycorrhiza




n. pl. mycorrhi·zae (-zē) or mycorrhi·zas
The symbiotic association of the mycelium of a fungus with the roots of a plant, as is found in the majority of vascular plants.

my′cor·rhi′zal adj.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


(Greek myco- fungus, rhiza root) an association between a FUNGUS and the roots of a higher plant. In some cases the fungus breaks down PROTEINS or AMINO ACIDS that are soluble and can be absorbed by the higher plant. In most cases, only nitrogen and phosphorus compounds result from fungal activity. Carbohydrates synthesized by the higher plants are absorbed by the fungus, so the relationship is a form of SYMBIOSIS. Some plants which lack chlorophyll, such as the bird's nest orchid, rely on mycorrhizas for carbohydrates in addition to protein.

There are two types of mycorrhiza: ectomycorrhiza and endomycorrhiza. In an ectomycorrhiza the infecting fungus occurs on the surface of the root and possibly between the cells of the root cortex, but does not penetrate such cells. The root becomes covered by a sheath of fungal tissue and looks different from an uninfected root. It is thicker, has no root hairs or root cap and may be a different colour. Ectomycorrhizae are found mainly on trees, such as oak and pine. In an endomycorrhiza the fungus develops within the cells of the root cortex. Subsequently the root cells digest the fungus leaving only knots of fungal material in the cells. There is usually little difference in the morphology of the root and a sheath of fungal tissue is not normally formed.

Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005
References in periodicals archive ?
Co-author Professor Holger Kreft, added, "The proportion of plant species with mycorrhiza interactions also increases from the poles to the equator".
Ethylene-dependent/ethylene-independent ABA regulation of tomato plants colonized by arbuscular mycorrhiza fungi.
In plant-fungus-bacterial association mycorrhiza helper bacteria (MHB) are reported to have positive influence in enhancing the efficiency and intensity of the ectomycorrhizal symbiosis (Brule et al., 2001; Cumming et al., 2015; Deveau et al., 2016; Dominguez et al., 2012; Izumi et al., 2006; Kurth et al., 2013; Mediavilla et al., 2016; Shakya et al., 2013; Zhang et al., 2010).
Cardoso, "Sporulation and diversity of arbuscular mycorrhizal fungi in Brazil Pine in the field and in the greenhouse," Mycorrhiza, vol.
Light and electron microscopy of a distinctive VA mycorrhiza in mature sporophytes of Ophioglossum reticulatum.
Integration of crop rotation and arbuscular mycorrhiza (AM) inoculum application for enhancing AM activity to improve phosphorus nutrition and yield of upland rice (Oryza sativa L.).
Phillips examines the connection between fungi (mycorrhiza) and soil, roots, and fertility with an eye towards cultivating more sustainable gardening and farming practices.