Medulla (lichenology)
Encyclopedia
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. The medulla generally has a cottony appearance. It is the widest layer of a heteromerous lichen thallus.
Lichen
Lichens are composite organisms consisting of a symbiotic organism composed of a fungus with a photosynthetic partner , usually either a green alga or cyanobacterium...
thallus. It is a loosely arranged layer of interlaced hyphae below the upper cortex
Cortex (anatomy)
In anatomy and zoology the cortex is the outermost layer of an organ. Organs with well-defined cortical layers include kidneys, adrenal glands, ovaries, the thymus, and portions of the brain, including the cerebral cortex, the most well-known of all cortices.The cerebellar cortex is the thin gray...
and photobiont zone, but above the lower cortex. The medulla generally has a cottony appearance. It is the widest layer of a heteromerous lichen thallus.