ascohymenial (adjective) – asci arranged within a true hymenium; referring to one of two general types of ascocarp development: in the ascohymenial ontogeny ascocarps formation initiates with the fertilization of the ascogon. The primordium subsequently differentiates into a true hymenium directly from the generative, ascogeneous hyphae. Layers of somatic hyphae only secondarily envelop this primordium. The ascohymenial development thus begins with fertilization and differentiation of generative hyphae, followed by the development of the ascocarp. The result is the formation of true apothecia, perithecia or cleistothecia. Especially lichen-forming fungi often have ascohymenial ascocarps that persist for several generations and new asci are formed within these perennial ascocarps with every new season. Therefore, the formation of new asci within an existing ascocarp must not be confused with an ascolocular ontogeny.