conidia

Conidia are asexual, non-motile spores produced by fungi, typically on specialized hyphae called conidiophores. They serve as the main means of rapid dispersal and colonization, enabling fungi to spread and establish new growth without engaging in a sexual cycle. Conidia are usually haploid and germinate directly to form new mycelium under suitable conditions. They differ from sporangiospores, which are formed inside sporangia in other fungal groups.

Conidiogenesis, the formation of conidia, occurs in various ways and structures. Conidiophores bear conidiogenous cells that generate conidia, often in chains or clusters. In some fungi, the conidia are produced by phialides on a vesicle, as seen in many genera of molds such as Aspergillus and Penicillium. Conidia can be unicellular or multicellular and vary widely in size and shape. Major types include blastoconidia, formed by budding from a parent cell; arthroconidia, formed by fragmentation of hyphae; and macroconidia or microconidia, which refer to larger or smaller forms in certain lineages. The terms blastic and thallic describe two fundamental modes of conidium development: blastic conidia form by enlargement of a conidiogenous cell before release, whereas thallic conidia arise by septation or fragmentation of the existing hypha.

Ecological and practical significance is broad. Conidia mediate dissemination of many plant and animal pathogens and can be a major contributor to allergic and infectious diseases in humans. They are also central to taxonomic identification and classification in medical and environmental mycology, as conidial morphology often provides key diagnostic characters.