# Mycorrhizae

> Mycorrhizae are symbioses in which fungi colonise plant roots and extend hyphae into the soil, trading water and nutrients such as phosphorus for the plant's sugars.

- Canonical: https://genetixbay.com/knowledge/glossary/mycorrhizae.html
- Also written: mycorrhiza, mycorrhizal fungi, myco, AMF, arbuscular mycorrhizal fungi, mycorrhizal inoculant
- Glossary category: Systems and media · Evidence: Supported
- Status: Draft: awaiting expert review · Updated: 2026-10-31
- Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay cannabis glossary"

A mycorrhiza is a mutualistic association between a fungus and a plant root. Cannabis forms arbuscular mycorrhizae (AM), in which fungi of the Glomeromycota grow inside root cortex cells and spread fine hyphae far into the soil. The hyphae explore a much larger volume than roots alone, improving uptake of phosphorus and other [immobile nutrients](https://genetixbay.com/knowledge/glossary/immobile-nutrient.md) and water, in return for carbon from the plant.

## In practice

Growers add mycorrhizal inoculants at planting or [transplant](https://genetixbay.com/knowledge/glossary/transplanting.md), dusting powder or granules where roots will contact them. Benefits are clearest in low-phosphorus soils and living-soil systems. High phosphorus fertilisation suppresses colonisation, so in heavily fed hydro or [coco](https://genetixbay.com/knowledge/glossary/coco-coir.md) the fungi have little to offer and often fail to establish. Many products contain few viable propagules; quality varies.

Evidence: established for many crops; for cannabis, studies are limited and results mixed.

## Don't confuse with

- **Trichoderma**: a beneficial root-zone fungus, but not mycorrhizal.
- **Mycelium (mushrooms)**: fungal threads in general; not all form symbioses with plants.

## Related terms

[Living soil](https://genetixbay.com/knowledge/glossary/living-soil.md), [Root zone](https://genetixbay.com/knowledge/glossary/root-zone.md), [No-till](https://genetixbay.com/knowledge/glossary/no-till.md), [Phosphorus](https://genetixbay.com/knowledge/glossary/phosphorus.md), [Compost tea](https://genetixbay.com/knowledge/glossary/compost-tea.md)

## Read more

- [Living soil (no-till, water-only organic growing)](https://genetixbay.com/knowledge/systems/living-soil.md)

## Sources

1. Smith SE, Read DJ, 2008. Mycorrhizal Symbiosis, 3rd ed. Academic Press.