Greater sulphur cup is a lichen with a squamulose thallus with a fruitcose podetia and red apothecia at the top of podetia. The thallus is yellow or yellow-green and made of squamules (scale-like thallus lobes) that are persistant. Squamules have white undersides, rhizines are absent, its podetia arise from the squamules and reach 85mm tall, are typically misshapen and cupped at the top.
It can be distinguished from other members of this large genus by a combination of factors. First, the podetia (tube-like columns arising from basal squamules), are irregularly shaped, unbranched, cup-like and have soredia. Secondly, its thallus typically has a yellowish hue. Finally, the small apothecia are red.
