Medulla (lichenology)

The medulla is a horizontal layer within a lichen thallus. It is a loosely arranged layer of interlaced hyphae below the upper cortex and photobiont zone, but above the lower cortex.^[1] The medulla generally has a cottony appearance. It is the widest layer of a heteromerous lichen thallus.

References

1. Galloway, D.J. (1992). Flora of Australia - Lichen Glossary "Flora of Australia Lichen Glossary. Copyright ABRS". Archived from the original on 2014-12-06. Retrieved 2014-09-30.