Conidia as modified hyphae

Abstract

An attempt is made at a unified morphological analysis of the hyphomycetous anamorph as seen in its two phenotypic expressions: the vegetative (=hyphae and mycelia) and the reproductive (=conidiophores, conidiogenous cells, proconidia and free propagules). (Multi-hyphal structures are ignored). A distinction is made between cytological and structural criteria. The basic units used arecells (or compartments), and their assemblage intohyphae, and at a higher level of organization,organs. The description ofelements (=the simplest recognisable structures) is suggested for cases where compartments are absent or poorly defined. Eight independent characters are proposed for the description of the mature anamorph. A unified approach is also suggested for the study of the development of the anamorph. Basic, general processes are growth (=different combinations of elongation, branching and transformation), maturation, lysis and secession (as defined in this paper), and, in the case of recognizable compartments, cell division (=septation). These processes, when integrated in various specific sequences, result in well known patterns, seen in both vegetative development and asexual reproduction. Examples are drawn from species with ameroconidia, more intensively studied in recent literature, as well as on lesser known species with simple, septate, or compound conidia. Some criteria are proposed for an ordered observation of independent processes which could provide a basis for a more stable descriptive terminology.