A procedure is described which provides mature meiosporangia of Allomyces macrogynus in 7 days or less. By variations in these conditions it was found that key environmental factors controlling maturation were a low total concentration of nutrients, controlled inoculum size and aeration, and a supply of tyrosine. Mature meiosporangia remained able to release spores for weeks as long as cultures were shaken at 30 °C. Spore release was initiated when cultures were unshaken. Methylene blue was useful for staining meiosporangia and was bound by the internal melanized layer. Spore cleavage was observed in the absence of spore release.