Largest known Umbilicaria mammulata specimen

What to remember

The thallus of Umbilicaria mammulata is usually 4 to 15 cm across. In the Smoky Mountains of Tennessee, however, specimens have reached 63 cm, making it the largest lichen.

The gap with the usual size is clear: the record specimen sits well outside the species' common range.

The size of a living thing can be measured by mass, volume, area, length or height. For this lichen, diameter is the measure.