The jack-o'-lantern mushroom is orange. Its bioluminescence, a blue-green color, can be observed in fresh specimens in low light conditions once the eye becomes dark-adapted. The whole mushroom does not glow — only the gills do so. Caps are 3 to 20 cm; at first convex, with a central bump or point; becoming more or less flat, and eventually shallowly vase-shaped - but usually retaining a small central "nipple"; bald; dry or slightly greasy; bright orange to pumpkin orange; the margin inrolled when young. Gills are running down the stem; close or crowded; bright orange to pale orange; luminescent when fresh. Stem is 3 to 13 cm long; 1 to 2 cm thick; tapering to base; solid; bald; pale orange to orange. Flesh is pale orange; unchanging when sliced.
Saprobic; growing in large clusters on the stumps or buried roots of hardwoods, especially oaks; late summer and fall;