Mold spores are tiny propagative units similar in function to plant seeds but they do not contain preformed embryo. They can be produced by sexual or asexual means.

Types of Mold Spores
Various terms are used to describe mold spores:

• Ascospores: spores produced by ascomycetes, e.g., those of the mold Chaetomium;
• Basidiospores: spores produced by basidiomycetes e.g., those of mushrooms;
• Conidiospores (conidia): spores produced by most members of the deuteromycetes, e.g., those of molds such as Aspergillus, Penicillium and Stachybotrys;
• Sporangiospores and Zygospores: spores produced by Zygomycetes, e.g., those of the mould Rhizopus.

Some mold spores can remain viable for many years.