Dictionary.net

Either of two diseases resulting from fungal infection of the hair shafts. Black piedra occurs mainly in and on the hairs of the scalp and is caused by Piedraia hortae; white piedra occurs in and on the hairs of the scalp, beard, moustache and genital areas and is caused by Trichosporon beigelii.

A disease of the hair occurring in Colombia, South America. It consists of nodular concretions on the hair, produced by a fungus which grows in the oil used for dressing the hair. The nodules are the size of a pins head and are so hard that they rattle when the hair is combed. [Sp.]