[4]: 65 The term dioecy is inapplicable to bryophytes because it refers to the sexuality of vascular plant sporophytes.
[6] The words dioicous and di(o)ecious are derived from οἶκος or οἰκία and δι- (di-), twice, double.
((o)e is the Latin way of transliterating Greek οι, whereas oi is a more straightforward modern way.)
[10] The ancestral sexual system in bryophytes is unknown but it has been suggested monoicy and dioicy evolved several times.
Sexual specialization has been used as an explanation for this recurring evolution of dioicy in mosses.