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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 ?
On the other hand, species with low AM colonization rates may be less reliant on the formation of AM and are therefore dependent on ephemeral patches of sufficient resource availability where mycorrhizae may not be available or beneficial (Janos, 1980; Endresz et al., 2013).
Influence of arbuscular mycorrhizae on biomass and root morphology of selected strawberry cultivars under salt stress.
Mycorrhizae are beneficial fungi that are found in plant roots and they promote plant growth and vigour.
Agerer (1986) described and identified the mycorrhizae of Spruce with Lactarius deterrimus, L.
Wedin, "Soil carbon, nutrients, and mycorrhizae during conversion of dry tropical forest to grassland," Ecological Applications, vol.
Growth responses of several plant species to mycorrhizae in a soil of moderate P-fertility Mycorrhizal dependency under field conditions.
This plain-language, color-illustrated guide for gardeners and cultivators explains how mycorrhizae fungi can help grow agricultural plants, flower gardens, and cannabis.
Major groups of mycorrhizae include ectomycorrhizae, endomycorrhizae, ericoid mycorrhizae, and orchid mycorrhizae [6-8].
Mycorrhizae known as root fungi, a symbiotic association formed between a fungus and the roots of a vascular plants.
Through MA and SyMyco Inc., a joint venture in which MA participates, VBC brings the world's foremost experts in the study and propagation of mycorrhizae - beneficial fungi that colonize plant roots to enhance nutrient uptake and water efficiency.