An
umbo is a raised area in the center of a mushroom
cap. Caps that possess this feature are called
umbonate. Umbos that are sharply pointed are called
acute, while those that are more rounded are
broadly umbonate. If the umbo is elongated, it is
cuspidate, and if the umbo is sharply delineated but not elongated (somewhat resembling the shape of a female breast), it is called
mammilate or
papillate.